GEO

Hot Spot Volcanism:

"hot spots" - points of upwelling mantle material (from the asthenosphere) - not necessarily associated with sea-floor spreading centers - they remain fixed relative to the moving plates - e.g., the Hawaiian Islands

Earthquake rating scales

"intensity scales": classify & describe damage to terrain & structures - "Mercalli Scale" - I-XII - barely felt - to - total destruction "magnitude scale": "Richter Scale" - based on wave amplitude at least 100 km from epicenter - it's open ended & logarithmic - each whole # represents a ten fold increase in measured wave amplitude

Two types of body waves:

"primary" & "secondary" - based on their mode of travel through materials P waves - are "push-pull" waves - they push (compress) and pull (expand) rocks in the direction the wave is traveling Solids, liquids, and gases resist a change in volume when compressed, and elastically spring-back after the force is removed; P-waves can thus move through all 3 materials S-waves: "shake" the rock particles at right angles to the direction of wave travel S-waves do not change the volume of the rock, but instead, change the "shape" of the rock material Since gases and liquids (fluids) don't respond elastically to changes in shape, S-waves can't be transmitted through fluids Surface waves: more complicated - an up-and-down motion (like ocean swells); plus a side-to-side motion similar to S-wave motion in the horizontal (very damaging to foundations) Differences in rock density and elasticity influence wave velocity. In solid rock: P-waves travel fastest - 1.7 X S-waves; Surface waves travel at 90% the velocity of S-waves

Which of the following is a characteristic of an S wave?

"shaking" particle motion at right angles to the direction of wave travel

Types of Chemical SedimentaryRocks:

(1) Limestone accounts for ~10% of the total volume of sedimentary rocks & is the most common chemical sedimentary rock is comprised mainly of calcite (CaCO3) is formed by either inorganic or organic processes marine biochemical forms (90%)are the most common forms of limestone: "coquina" - (a limestone) comprised of poorly cemented calcite-rich shells sedimentary rock - e.g., "chalk" - a soft porous rock composed of the shells of microscopic sea organisms Inorganic Limestones: form when the concentration of CaCO3 increases to the point where it precipitates examples: "travertine" (seen in caves);

Settings of Metamorphism

(1) Regional Metamorphism produces the greatest volume of metamorphic rocks occurs during mountain building when great quantities of rock are subjected to the intense stresses and high temps associated with large-scale deformation—resulting in extensive areas of metamorphic rocks (2) Contact Metamorphism occurs when rock is in contact with, or near, a mass of magma the changes are caused primarily by the high temperatures of the molten material, which "bake" the surrounding rock

The Upper Mantle:

(1) outermost upper mantle = "high velocity zone" - just below the crust; 45-70 km thick; a rigid, cool layer - seismic waves are transmitted through readily (2) "asthenosphere" - from ~ 70-250 km - is a plastic layer; contains hot pockets due to radioactive decay; least rigid layer of the mantle; avg. density ~ 3.3 g/cm3; movement here causes crustal movements; convection occurs (3) remainder of upper mantle - 250-670 km - here rocks are solid because of increased pressures

Physical properties used to identify minerals

(1)Crystal Form crystal form is the external expression of a mineral's orderly internal atomic arrangement if the mineral has sufficient space while forming, it will develop well formed crystals (e.g., pyrite w/cubic faces; quartz w/hexagonal faces) if space is limited, crystal growth is stunted and the mineral will not exhibit its crystal form (2) Color an obvious but unreliable property of a mineral a mineral which comes in several colors, has "exotic coloration" (e.g., quartz) ( 3) Cleavage cleavage is the tendency of a mineral to break along certain planes where the bonds are weak (e.g., the micas) some minerals have several cleavage planes, some have poor cleavage, some have no cleavage (e.g., quartz) (4) Fracture minerals without cleavage exhibit fracture one such specific type of fracture is "conchoidal fracture" - broken glass like other fracture types: splintering, fibrous, irregular (5)Specific Gravity the ratio of the minerals density to that of water (the density of water = 1 g/cm3) o specific gravity = density of mineral / density of water the specific gravity of common rocks = 2.5 to 3.0 specific gravity of galena = 7.5; specific gravity of gold = 20 (these are far less common minerals) (6) Streak streak is the color of a mineral in its powdered form it is obtained by rubbing a mineral across a porcelain "streak plate" while mineral color may vary form sample to sample, streak typically does not (7) Luster luster is the way in which a mineral reflects light the capacity to reflect light depends on how smooth a crystal surface is at the atomic level e.g.: metals have metallic luster; nonmetals: glassy (vitreous), pearly, silky, earthy (dull) (8) Hardness a measure of the resistance of a mineral to scratching a mineral's hardness can be compared to that of minerals having a known hardness - "Mohs Scale"

Chemical Bonds-

(Recall: like charges repel and unlike charges attract.) - Question: what is it that holds materials together? - Answer: "electrostatic charge" (the attraction of positively charged objects for negatively charged objects draws materials together). It is this attractive force that holds or "bonds" these materials together. We say that a "chemical bond" has formed. when two or more elements have bonded together in definite proportions, a "compound" has been formed When two atoms bond they try to "reach a state of lowest possible energy". This is accomplished by "filling-up" the electron shells; with the lower most shells being filled-up first. the first principal shell (k-shell), holds a maximum of 2 electrons, while each of the higher shells holds 8 or more electrons the outermost shell (with the exception of the first shell), however, can hold no more than 8 electrons the outermost shells are usually involved in bonding; & would like to have a full compliment of electrons ("octet rule") - to become stable to satisfy the octet rule, atoms may either gain, lose, or share electrons with one or more atoms

(Locations of Volcanic Activity) (3) At hot spots

(e.g., Hawaiian Islands)

(Locations of Volcanic Activity) (2) Along sea-floor spreading centers and divergent boundaries on continents

(e.g., Iceland) & continental rift zones (e.g., rift zone in East Africa)

Uniformitarianism (James Hutton, late 1700's) - (the present is the key to the past)

* physical, chemical, and biological laws that operate today have also operated in the past * the forces and processes that we observe shaping the Earth today, have been operating for a very long time * geologic processes occur over very long periods of time

(1)Silicate Minerals(The Silicates)

- (must contain oxygen & silicon) most rocks are made of silicate minerals!! meaning, they are the most common mineral group!! silicate minerals: olivine, pyroxene, amphibole, mica, feldspar and quartz the fundamental building block of the silicates is the: "silicon-oxygen tetrahedron" 4 oxygen atoms & 1 silicon atom (SiO4)^4-its an ion, not a compound: its "incomplete", thus unstable each oxygen ion provides a charge of -2 the silicon ion provides a charge of +4 the tetrahedra become stable when positive ions are added to them (iron, magnesium, potassium, sodium, and calcium) these ions also connect the silicate structures (i.e., the chains, sheets, and 3-D structures) the feldspars are the most abundant silicate group - comprising over 50% of the Earth's crust quartz (SiO2)is the second most abundant mineral in the Earth's crust

The Geologic Cycle

- a term that characterizes the cycling that takes place at the Earth-Atmosphere interface. The Earth's crust is in a constant state of flux.

Absolute Dating

- absolute dating pinpoints the time in history when some geologic event took place. Our understanding of radioactivity allows us to accurately determine absolute dates for rock units that represent important events in Earth's past.

Earthquakes

- an earthquake is the vibration of the earth produced by the rapid release of energy. Most earthquakes are caused by the slippage along a fault in Earth's crust.

Gold has a specific gravity of almost 20. A 5-gallon bucket of water weighs 40 pounds. How much would a 5-gallon bucket of gold weigh?

800lbs

What is the temperature above which magnetite loses its magnetization?

800°C

(1) Tsunamis generation

- earthquakes, volcanic eruptions, submarine landslides

Fossil Succession

- fossil organisms succeed one another in a definite and determinable order, and any time period can be recognized by its fossil content.

"rock cycle"

- generates the three basic rock types of the Earth's crust

"rock cycle"

- generates the three basic rock types of the Earth's crust eight elements comprise 99% of the Earth's crust two of these elements - oxygen & silicon - account for 74% of the Earth's crust a mineral (defn): an element or combination of elements that forms an inorganic, naturally occurring, solid ; it has a definite chemical composition, and must have an orderly internal structure (i.o.w., has a crystalline structure) 4,000 minerals - only 20 are common - 10 of the 20 make up 90% of the minerals in the crust a "rock" - an assemblage of one or more minerals bound together; the properties of the individual minerals are retained - thousands of rock types. (Note: the properties of elements are not retained in minerals.) all rocks form from one of the following 3 processes: igneous, sedimentary, and metamorphic processes

C. Metamorphic Agents

- heat, pressure, & chemically active fluids rocks are often subjected to all three agents simultaneously the degree of metamorphism and the contribution of each agent varies greatly from one environment to another additionally, the mineral composition of the parent rock determines to a large extent the amount of metamorphism—e.g., quartz sandstone vs. limestone

"tectonic cycle"

- moves heat energy and material to the surface, creating crustal movement & deformation

"normal" (tension) fault

- moves vertically along an inclined fault plane

Superposition

- in an undeformed sequence of sedimentary rocks or lava flow, each bed is older than the one above, and younger than the one below

seismographs

- instruments that record earthquake waves

Geologic Time (ON GOOGLE DOC PICTURE)

- is very long - Earth is 4.6 billion years old - based on "radiometric (absolute) dating" methods as well as "relative dating" techniques Geologic Time Scale - Eons, Eras, Periods, and Epochs

"focus"

- the subsurface area along the fault plane where the quake (seismic wave) is initiated

(2)Nonsilicates (the nonsilicate minerals)

- make up 1/4 of continental crust they have important economic value !! carbonates CO32-+ pos. ions - e.g., calcite (limestone), dolomite (dolostone) halite - "table salt" gypsum - used to make plaster

"Metamorphism"

- means to "change form" metamorphism changes existing rocks in size, shape, texture, and even the minerals they contain. metamorphic rocks can form from igneous, sedimentary, or even from preexisting metamorphic rocks heat, pressure, and chemically active fluids are the agents of metamorphism The amount of metamorphism varies in degree o low-grade metamorphism - rocks are only slightly changed; e.g., shale to slate - samples are hard to distinguish o high-grade metamorphism - the transformation is so complete that the identity of the original rock cannot be determined - features of the original rock (e.g., fossils, bedding planes) are obliterated as well o in the most extreme metamorphic environments, temperatures approach those at which rocks melt. However, during metamorphism, the deformed material must remain solid, for if melting occurs, the rocks would be considered igneous The formation of metamorphic rocks takes place within the Earth's interior o at the elevated temperatures and pressures of the region extending from a few kilometers below the Earth's surface to the crust-mantle boundary o since this process is hidden form view, metamorphism is one of the hardest processes for geologists to study extensive areas of metamorphic rocks are exposed on every continent metamorphic rocks are an important component of many mountain belts—they make-up a large portion of the mountain's core even the stable continental interiors, which are covered by sedimentary rocks, are underlain by metamorphic rocks

"strike-slip" (transform or lateral) fault

- movement along fault line is horizontal - e.g., San Andreas Fault

"aftershock"

- occurs after the main shock

Ionic Bonds (involve ions):

- one atom gives-up an electron; and the other receives that electron (permanently). - so now you have a positively charged ion (cation) and a negatively charged ion (anion). - the attractive force between the two oppositely charged ions holds (bonds) them together. - in the case of sodium (Na) and Chlorine (Cl), Na has 1 extra electron, Cl one too few; so, Na gives its electron to the Cl to make NaCl (sodium chloride, table salt). - both atoms now have full orbitals; they have reached their lowest energy state. - the Na is now positively charged, having given-up and electron - while the Cl is negatively charged, having received the extra electron. The attractive electrostatic force holds them together.

"foreshock"

- precedes the main shock - may be related to the breaking of a few asperities prior to the main quake

Relative Dating

- rocks and structures are placed in proper sequence or order - only the chronological order of events is determined - absolute ages are not determined - it is accomplished on the basis of the "law of superposition"

"fault plane"

- surface along which both sides of the fault move

"epicenter"

- the area at the surface directly above the focus

Catastrophism

- the non-scientific notion that the Earth was shaped by catastrophic events/disasters of a short-term nature - Earth created in ~ 4,000 BC - NO SCIENTIFIC evidence!!)

The Covalent bond:

- the outer electrons between two atoms are "shared". - results when the outer shells of adjacent atoms are both half filled. - the electrons in the outer shells rapidly travel between the adjacent atoms and act to fill both shells. - covalent bonds are the bonds that hold your body tissue and DNA together. They are very common in nature.

seismograms

- the record made by a seismograph

Fossils

- the remains or traces of prehistoric life

seismology

- the study of earthquake waves - Chinese ~ 2,000 yrs ago

"reverse/thrust" (compression) fault

- vertical movement along an inclined plane - here stress is due to compression

isostasy

- with a greater load (e.g., when mountains lie above the crust) the crust rides lower in the asthenosphere; when some of the load is removed (e.g., due to erosion) the crust rides higher in the asthenosphere - "isostatic rebound" Thus, the crust is always rising or sinking in response to its own changing weight

Which of Hawaii's five volcanoes are still considered to be active? -Kohala -Mauna Kea -Kilauea -Mauna Loa -Hualala

-Kilauea -Mauna Loa

Metallic Bonds:-

-are involved in the bonding of metal compounds. - the atoms of metals (gold (Au), iron (Fe), aluminum (Al), etc.) typically have filled outer shells plus one or more extra electrons. - after two metals combine these extra electrons (neg. charges) move throughout the material freely, while the protons in the nuclei create centers of positive charge. The resulting attractive forces between the flowing electrons and the positive nuclei hold the metal compound together.

Which materials in Hawaii's lava help to keep it fluid for longer at the surface (as opposed to cooling and solidifying quickly), thus allowing extensive lava flows to develop? -silica -iron -sulfur -water -magnesium

-iron -magnesium

On average, how many damaging earthquakes occur each year?

1000

At what age can children work in the mines of Cerro Rico?

14

What is the range of dome complex height?

500 to 2,000 meters

Elements and Periodic Table

19th-century scientists discovered that all substances could be formed by using only 92 basic building blocks called elements: the basic building blocks of minerals Today, over 100 elements are known - although some have been produced only in the lab most minerals are a combination of two or more elements, joined (bonded) to form a compound; (some minerals are made from just one element) The elements were arranged into a Periodic Table by Dimitri Mendelev about 1870. The elements were organized in such a way that their properties, similarities, and differences could be predicted from their position on the table. Each element has a name and is abbreviated with a 1 or 2 letter symbol. E.g., H for hydrogen; He for helium; and O for oxygen. Each element has its own box on the table. Elements in the same columns have similar chemical behavior. Each element (box) has an atomic number and an atomic mass. * Atomic Number = the number of protons in the nucleus (= the # of electrons in an electrically neutral atom). * Atomic Mass (atomic weight) = the mass of the atom. (Results from the number of protons and neutrons which reside in the atom's nucleus.) The elements are made up of individual units called atoms - the smallest part of matter that still retains the characteristics of an element

What is the typical rate of seafloor spreading in the Atlantic Ocean?

2 centimeters per year

(2) Pangaea

225-200 M.Y. ago - Triassic-Jurassic - a "supercontinent" with areas of N.A., N. Africa, the Middle East, & Eurasia near the equator & covered w/abundant vegetation the Atlantic Ocean was non-existent

How much money does Omar earn mining at Cerro Rico?

30 US dollars a week

What is the range of shield volcano height?

300 to 10,000 meters

What is the average lifespan of a Cerro Rico miner?

40 years old

(1) Pre-Pangaea

465 M.Y. ago - mid-Ordovician - S.A., Africa, India, Australia, & S. Europe are part of Gondwanaland in the S. Hemisphere; Greenland & N.A. are part of Laurentia

Movement of plates away from each other at divergent boundaries typically shows which of the following average velocities?

5 cm per year

Igneous Rock Processes

:igneous rocks solidify & crystallize from a molten state - from a magma (molten rock beneath the surface) magma is either intruded into preexisting strata (country rock); or extruded onto the surface - "lava" the rock's texture and degree of crystallization is a function of how quickly the magma cools o fast cooling = fine grained or glassy o slow cooling = coarse grained

Which of the following is a characteristic of a conglomerate?

A conglomerate is made up of course grains that are poorly sorted.

What causes the volcanoes and deep valleys of East Africa?

A continental rift along parts of the African continent beginning to slowly separate

What type of boundary occurs along the Aleutian Islands in the North Pacific?

A convergent boundary on a volcanic arc above the northward-subducting Pacific plate

Pyroclastic material is ejected from a volcano during an explosive eruption. These fragments are defined by their size, which ranges from less than 2 mm to greater than 64 mm. Ash is less than 2 mm in diameter, with an appearance of dust or sand. Lapilli, or cinders, range from 2 mm to 64 mm in diameter. These pyroclasts are commonly pea to walnut sized. Blocks and bombs represent the largest fragments, which are greater than 64 mm. Blocks are erupted as hardened lava with a mostly angular shape, while bombs are semi-molten and develop a streamlined-shape while flying through the air.

A outlines lapilli, which are particles ranging from 2 to 64 mm in diameter. Label B shows a volcanic bomb, which is greater than 64 mm. This fragment is characterized by its streamlined appearance, shown by the small ridges or lines along the surface. The size of the hammer provides assistance to answering this question. The hammer, which is 265 m in length, is clearly larger than the lapilli and smaller than the volcanic bomb.

A continental volcanic arc is formed when which of the following conditions exists?

A piece of oceanic crust is subducted below continental crust.

What type of region is the modern-day Red Sea?

A rift zone that may eventually open into a major ocean if Arabia and Africa continue to separate

What causes the same mineral to occur in varieties that are different colors

A small amount of impurities in the crystal structure

What is the difference between aa lava and pahoehoe lava?

Aa lava has a prickly texture; pahoehoe has a smooth, ropy texture.

If a sequence of sedimentary units is cut by a fault, what does the principle of cross-cutting relationships tell a geologist?

All of the sedimentary units must have been deposited and lithified before being cut by the fault.

Earth and distance from center

Always keep in mind that the earth gets less dense and cooler with distance away from the center of the earth

In addition to viscosity, which of the following parameters has an influence on whether a volcanic eruption will be effusive or violent?

Amount of gas in the magma. In addition to the viscosity, the amount and type of gas in the magma or lava can influence the eruption of a volcano. As pressure on the magma or lava is reduced, the gas can escape violently, causing a large eruption.

Although new crust is being formed at divergent boundaries, Earth remains the same size. Which of the following statements provides the best reason for this?

An equal volume of crust is being consumed at convergent boundaries.

Bonds

An ionic bond is the attraction of oppositely charged ions to one another, producing an electrically neutral compound. In the ionic bond, one atom gives up one or more of its valence electrons to form ions—positively and negatively charged atoms. The atom that loses electrons becomes a positive ion, and the atom that gains electrons becomes a negative ion. Oppositely charged atoms are strongly attracted to one another and join to form ionic compounds.

How do we generate magma from solid rock?

Answer(s): ** raise the temperature above the rock's melting point **one source of heat is that which is released by the decay of radioactive minerals found in the Earth's mantle & crust ** additionally, as pressure decreases, the melting point decreases ** when water (and other fluids) are introduced, melting temperatures are lowered ** recall that silica rich rocks melt at a lower temperature than basaltic rocks - "partial melting" ** partial melting of rock often produces a granitic magma - produces most, if not all, magma

In general, where do earthquakes AND volcanic eruptions occur?

At both divergent plate boundaries AND convergent plate boundaries.

Chemical Bonds

Atoms attach to one another creating compounds and the chemical structure of minerals. The attachments, called bonds, form when an electron is transferred from one atom to another or shared between atoms. The electrons in the outermost shell of an atom are usually involved in forming bonds. Through chemical bonding, atoms fill their outermost shell until it contains eight electrons. Once the outermost shell is full, it is stable and will not bond. This is known as the octet rule. Atoms on the far right side of the periodic table (the noble gases) contain eight electrons in their outer shell and will not bond with other atoms. Atoms that have eight electrons in their outer shell—the noble gases—are stable and will not form chemical bonds with other atoms according to the octet rule. Other atoms are likely to either give up an electron to another atom, bonding the two together, or share an electron between atoms.

Which of the following is an accurate description of ionic bonding?

Atoms of different elements, having gained or lost electrons, form negative and positive ions that are bonded together by attractive forces between ions with opposite charges.

What are shield volcanoes generally made of?

Basalt flows

What are composite volcanoes made of?

Basalt flows Pyroclastic deposits

Which of the following rocks best represents the typical composition of oceanic crust?

Basalt.

Which of the following types of lava will most likely lead to a volcanic eruption of an effusive nature?

Basaltic. The low silica content of basaltic lavas produces low viscosity and tends to make volcanic eruptions quiescent and effusive.

Which of the following responses best describes why the lithospheric plates are able to move around on the surface of Earth?

Because the asthenosphere is composed of weak, hot, and dense rock, the cold, rigid, less dense lithospheric plates are capable of moving on it.

What is the name of dark-colored mica?

Biotite

Where do body waves and surface waves travel?

Body waves travel within Earth, and surface waves travel along Earth's surface.

What do vertical and horizontal surface waves have in common?

Both waves travel along Earth's surface and decrease in amplitude with depth below the surface.

What mineral is not scratched by fingernail but scratched by copper penny

Calcite

Which carbonate mineral reacts readily with cool, dilute hydrochloric acid (HCl) to produce visible bubbles of carbon dioxide gas?

Calcite

What are the two important processes involved in lithification of sedimentary rocks?

Cementation and compaction

The process of diagenesis (SAND INTO SANDSTONE)

Clastic sedimentary rocks are formed during a process called diagenesis. It is similar for many sedimentary rock types. Here is the process described specially for the diagenesis of sand into sandstone. Imagine a large deposit of loose sand sediment along a shoreline. Over a great amount of time, the sand is compacted as more and more sand is piled on top. Greater depths increase heat and pressure, which cause the sand to cement together, and become sandstone. Over time, the material above the sandstone will be eroded, as will the sandstone. Sedimentary rocks that have clasts prone to falling off are said to be poorly cemented, while rocks with clasts firmly in place are well cemented.

What is the tendency of certain minerals to break along smooth, parallel planes called?

Cleavage

Which of the following best describes the term cleavage

Cleavage of the splitting of minerals along natural plains of weakness

Quartz exhibits

Conchoidal fracture

Which of the following is the volcanic feature in which magma rises through before it is released at the surface?

Conduit

Which region of Earth is composed of abundant amounts of granite?

Continental crust.

Suppose you found A mineral crystal that look like Topaz what to minerals could you use any scratch test to help determine if the mineral is in the Topaz

Corundum and quartz

In which type of chemical bonding are electrons shared between adjacent atoms?

Covalent

In studies of rock obtained from ocean basins all over Earth, the oldest ages obtained are approximately 200 million years before the present. Why have no older oceanic rocks been discovered?

DUE TO TECTONIC ACTIVITY, ROCKS ON THE OCEAN FLOOR ARE CONTINUALLY RECYCLED.

Why are mineral bands in metamorphic rocks light and dark colored?

Dark minerals rich in iron and magnesium separate from light minerals rich in silica and aluminum.

There are two types of sedimentary rocks:

Detrital Sedimentary Rocks - are formed from solid particles - derived from both physical and chemical weathering o (weathering: the disintegration and decomposition of rock at or near the surface of earth; erosion: the incorporation and transportation of material by a mobile agent, such as water, wind, or ice) Chemical Sedimentary Rocks - are formed from soluble material, produced largely from chemical weathering o these dissolved materials are precipitated by either inorganic or organic processes

What mineral is the hardest known substance in nature?

Diamond

Name the hardest and softest mineral of the moh's scale

Diamond hardest and talc softest

Ancient Climates (Paleoclimates)....

E.g., near the end of the Paleozoic era (220-300 million years ago), ice sheets covered extensive areas of the Southern Hemisphere - layers of glacial till were discovered in southern Africa, South America, Australia and India - in present-day subtropical and tropical climates

Which one of the following is an important fundamental assumption underlying the plate tectonic theory?

Earth's diameter has been essentially constant over time.

As stress is applied to rocks and deformation occurs, which of the following terms best characterizes the energy that is stored in the process?

Elastic energy

Which of the following responses provides the best reason for why the asthenosphere is not capable of storing elastic energy?

Elastic energy can only be stored in cold, brittle rocks.

What are the lightest in weight or least massive of the basic atomic particles?

Electrons

What discourages minerals from achieving habit?

Enclosed spaces

The geologic time scale

Eons are the longest span of geologic time on the graphic above and are represented by the tallest box on the far left. The next box represents an era, followed by periods, and epochs. The shortest boxes on the far right represent the shortest length of geologic time on the graphic, an age.

Most earthquakes are the result of movement along which of the following features?

Faults

Components of Atoms

Everything is made of atoms. Atoms are the particles that make up minerals (and all elements). Each atom is composed of protons and neutrons at its center, or nucleus, and electrons, which surround the nucleus. Electrons have very little density and a charge of −1. Protons have higher density and a charge of +1. With the same number of electrons and protons, an atom is electrically neutral—it has no electrical charge. Neutrons have the same density as protons and no electrical charge. The atomic number, shown in the key in the periodic table of elements below, represents the number of protons in an atom. This determines an atom's chemical and physical characteristics as well as which chemical element it is; elements with similar properties are arranged in columns (groups) below. The mass number, which is the atomic weight of an element rounded up, is equal to the number of protons plus the number of neutrons in an atom. There can be several variations of a chemical element, which are known as isotopes. While an element maintains the same number of protons, the number of neutrons differs between isotopes.

Which of the following processes can be observed at the margins of lithospheric plates?

FAULTING EARTHQUAKES VOLCANOES MOUNTAIN BUILDING

What type of magma erupts out of dome complexes?

Felsic magma

An igneous dike cuts through limestone, but not through the overlying sandstone. Which of the following statements is most accurate?

First, the limestone was laid down, then intruded by the igneous dike, and lastly the sandstone was deposited.

The point within Earth from which earthquake wave energy radiates is known by which of the following terms?

Focus of the earth quake.

Which of the following describes the principle of original horizontality?

Folded sedimentary layers were originally laid down flat and later deformed.

What are the two most important driving forces of metamorphism?

High heat and pressure

Which of the following events allows rocks on either side of a fault to rebound elastically, causing an earthquake?

Friction along the fault plane is overcome.

Which of the following exhibits three sets of cleavage and 90 angles

Galena

Lava flow outcrop

Geologists determine the geologic history of an area by observing rock units exposed in outcrops and analyzing their spatial relationships. The Law of Superposition: sedimentary rock beds lower on an outcrop are older than the rock beds above. The Principle of Original Horizontality: beds of sedimentary rock were originally deposited as flat-lying, horizontal layers. The Principle of Lateral Continuity: layers of sedimentary rock, when formed, extended horizontally in all directions. Gigapan technology mosaics thousands of photos together into a single image, allowing you to zoom in and see the tiniest of details. Imagine zooming in on a grain of sand on a photo of a beach!

In general, where do volcanoes form in subduction zones?

In general, volcanoes form on the overriding plate, away form the convergent boundary.

The P-wave Shadow Zone ....

German seismologist Beno Gutenberg noted a 35 degree zone where P-waves are absent - the "P-wave shadow zone" the shadow zone is produced by the bending of P-waves as they enter material unlike that of the overlying mantle since S-waves could not move through this area - the outercore - it was concluded that at least a portion of it was liquid The greater velocities of P-waves in the inner core provided evidence that it was comprised of solid rock in the asthenosphere (~ from100-350 km down), S waves have a lower velocity, indicating that this zone consists of hot, weak rock - a "plastic" - easily deformed ****as much as 10% of the material in the asthenosphere may be molton

Why glass is not considered a mineral?

Glass has a disorderly atomic structure

What was the name of the fossil flora that grew on Pangaea during the late Paleozoic?

Glossopteris

Which of the following has the highest specific gravity?

Gold

How does gypsum form?

Gypsum forms from evaporation of shallow seas by a chemical process.

The Anthropocene represents the first time that humans have played a pivotal role in the functioning of Earth as a system. There are both positives and negatives of this fact, and it is our responsibility to ensure that the positive impacts outweigh the negative ones in the future. For the options below, decide whether each is a negative or a positive outcome of humans' role in the Anthropocene.

Human activity has had both negative and positive impacts during the Anthropocene. Burning fossil fuels and cutting down forests for urban expansion are examples of how humans are detrimentally impacting natural areas. However, during the Anthropocene, humans have also discovered technologies that improve average lifespan and help to ensure that there is enough food for everyone on the planet. At the same time, natural areas have been preserved, which is another positive impact humans have had during the Anthropocene.

Which of the following is a mineral?

Ice

Which of the following best defines a mineral and a rock?

In a mineral, the constituent atoms are bonded in a regular, repetitive, internal structure; a rock is a lithified or consolidated aggregate of different mineral grains.

Igneous Rock Types:

Igneous rocks are categorized by texture & composition: "Felsic" igneous rocks - derrived from feldspar & silica (minerals) - are high in silica, aluminum, potassium, & sodium - have low melting points, are light in color, & are less dense than mafic rocks "Mafic" igneous rocks - derrived from magnesium & iron - are darker in color, & are more dense than felsic rocks granite is a coarse grained, intrusive, (thus cooled slowly) felsic rock basalt (comprises the bulk of the ocean floor) is a fine grained, extrusive (cooled quickly) mafic rock

Common Detrital Sedimentary Rocks:

In order of increasing particle size: shale, sandstone, conglomerate or breccia

_____ igneous rocks are those that cool below the surface.

Intrusive Intrusive igneous rocks form by the cooling and solidification of magma beneath the surface.

What element is principally responsible for making olivine, pyroxene, amphibole, and biotite dark?

Iron Iron is common in mafic rocks and minerals; in fact, "mafic" refers to the high iron and magnesium content of these materials.

Anthropocene epoch

It can be argued that we are now living in the Anthropocene, which is an epoch in the Cenozoic era that follows the Holocene epoch. It is the only span of geologic time that is defined by the impact of human activity on Earth, where our activities have caused mass extinctions and many other significant environmental changes. Although many scientists agree that we are living in the Anthropocene, many debate as to when the epoch began. Some scientists argue that the Anthropocene originated with the development of industrialized agriculture some 8,000 years ago, yet others think it began with the expansion of modern cities around the time of the Roman Empire (~2,000 years ago), while others believe it coincided with the Industrial Revolution about 300 years ago.

Which of the following volcanic materials flows out of a volcanic vent?

Lava. Lava leaves the volcano along the surface of the volcano. Material that is ejected into the air is called pyroclastic material.

Which Elements Will Bond?

Likely to bond: Sodium and Chlorine Potassium and Chlorine Magnesium and Oxygen Potassium and Bromine Unlikely to bond: Oxygen and Krypton Lithium and argon Hydrogen and Neon

Since color is not a very useful way to identify minerals what other optical property or properties can be used Since color is not a very useful way to identify minerals what other optical property or properties can be used

Luster and streak

Which of the following scenarios best describes how the Hawaiian Islands formed in the Pacific Ocean?

Magma generated from a hot spot burned through the overlying plate to create volcanoes.

What is the difference between magma and lava?

Magma is molten rock located below the surface; lava is molten rock erupted above ground

Origin of Magma

Magma originates from solid rock in the crust and mantle

Viscosity of Magmas Summary Table

MagmaType Solidified Rock Viscosity Basaltic Basalt Low Andesitic Andesite Intermediate Rhyolitic Rhyolite High

Two of these statements are true of conglomerate sedimentary rock similar to the one shown in the Gigapan image. Select the two correct statements.

Many of the clasts in this rock have rounded edges. & Many of the clasts within this rock are larger than sand.

Which of the following objects has a size similar to that of lapilli?

Marble (15mm) Lapilli are pyroclastic material that have diameters between 2 and 64 mm.

An igneous rock becomes buried, is subject to high heat and pressure, and recrystallizes. This rock then is eroded, transported, deposited and subsequently lithified. Which rock types—in order—did the original igneous rock develop into?

Metamorphic and sedimentary

Volcanic ash is best described as which of the following?

Microscopic pieces of rock ejected by a volcano. Volcanic ash is a very small piece of volcanic rock that is thrown into the air by a volcano.

Which of the following statements about divergent boundaries is true?

New ocean crust is created at a divergent boundary

Regardless of their size, most rocks are made up of __________.

Minerals

Gold and Quartz are minerals

Minerals are fundamental components of rocks and have great economic and commercial significance to humans. Therefore, geologists need a set of characteristics to identify and describe what makes an object a mineral versus something synthetic (such as plastic, for example). The criteria that defines matter as a mineral is that it is inorganic, composed of an orderly crystalline structure, solid, naturally occurring, and can be expressed by a chemical formula. Some matter looks very similar to minerals, but does not quite meet the criteria. For example, consider glass and quartz. Both are transparent and can have similar appearance. Glass does not have an orderly internal structure; its silica atoms are randomly arranged. Thus it is not a mineral. Quartz, however, has an organized chemical structure of silica atoms, each surrounded by four oxygen atoms and is a mineral.

Why do bands of minerals form when rocks are put under normal stress?

Minerals dissolve, atoms migrate to new locations, and minerals reform.

A scientist creates diamonds using high-pressure laboratory experiments. These diamonds are not considered minerals because which of the following requirements has been violated?

Minerals must occur naturally.

(4) Tsunamis Hazard Mitigation

Monitoring earthquakes around the Pacific Rim.

In general, how often do most cinder cones erupt?

Most cinder cones erupt once.

Which of the following statements regarding transform plate boundaries is not correct?

New oceanic crust is formed at transform plate boundaries. Crust is neither created nor consumed at transform plate boundaries.

What forms at divergent plate boundaries?

New oceanic lithosphere

Could metamorphic rocks reach the surface of a planet without rock-uplifting processes?

No, metamorphic rocks must be uplifted and exposed by erosion.

What causes the linear patterns associated with paleomagnetism on either side of mid-oceanic ridges?

Normal and reversed magnetized strips roughly parallel to the ridge

Observations Vs. Evidence

Observations are things that Wegener saw, such as coastline similarities and the breakup and movement of sea ice. The evidence he used to support these observations include continental sides fitting like a puzzle, and fossils and plant remains found in multiple continents.

Earthquakes with a deep focus are most often associated with which of the following tectonic settings?

Oceanic Trenches

The magnetic field of Earth is thought to originate in which of the following layers?

Outer core. Because the outer core is iron-rich liquid, the vigorous churning of this material as Earth rotates produces the magnetic field

The production of magma (magmatism) at divergent boundaries is characterized by which of the following?

Outpourings of lava/magma originating from the mantle. Melting caused by decompression

Throughout its history, how many people are estimated to have died from mining accidents and mining-related illnesses due to working underground at Cerro Rico?

Over 8 Million

What element is the most abundant in Earth's crust by weight?

Oxygen

Name two types of body waves.

P & S waves

Which of the three types of seismic waves travels through rock with the greatest velocity?

P waves

Other things found

Pecopteris was one of the seed ferns of the Paleozoic fossil forests. Calamites was a scouring rush of the Pennsylvanian fossil forests. Mesosaurus was an aquatic fish-catching reptile whose fossil remains are limited to black shales of the Permian period (about 260 million years ago) in eastern South America and southwestern Africa.

How do plates move at divergent plate boundaries?

Plates move apart

How do plates move at convergent plate boundaries?

Plates move toward one another.

How do plates move at transform plate boundaries?

Plates slide past one another.

Metamorphic rocks can form when which of the following conditions are met?

Pre-existing rocks undergo metamorphism when they are subjected to heat and pressure without melting.

Inorganic vs. Organic (Biochemical) Chemical Sedimentary Rock:

Precipitation occurs in two ways: (1) via "inorganic" processes (e.g., evaporation; chemical reactions); and (2) via the organic (life) processes of marine organisms - "biochemical" processes (e.g., when sea dwelling organisms extract calcite (CaCO3) and silica (SiO2) from seawater to build their shells; when the organisms die, their silica/calcite shell collect on the ocean floor and form biochemical sediment.

How are metamorphic rocks formed?

Preexisting rock is altered through heat and pressure.

Which of the following denotes the massive, positively charged, nuclear particles?

Protons

Basaltic igneous rocks contain which of the following minerals?

Pryoxene and calcium-rich plagioclase feldspar

In the field, you find an unidentified mineral that is clear, exhibits conchoidal fracture, and can scratch glass. This mineral is most likely:

Quartz

Which of the following substances is a mineral?

Quartz

Mineral descriptions

Quartz is a common light-colored silicate mineral that consists entirely of silicon and oxygen. Calcite is a carbonate mineral that effervesces when hydrochloric acid is placed on it; it exhibits cleavage in three directions, not at 90°. Olivine is a dark high temperature silicate mineral that is black to light olive green in color. Sometimes it exhibits a glassy luster and conchoidal fracture.

The spectrum of silicates

Quartz is pure silica, and at the other end of the spectrum we have olivine, which is silica poor and an iron and Mg rich, silicate mineral. Silica rich silicates crystallize-out of a cooling magma at lower temperatures, while olivine and pyroxene crystallize-out at higher temperatures.

oldest to youngest

Recall from the video that cinder cones form by explosive eruptions, which eject pyroclastic material. The pyroclastics build up the flanks of the volcano through time. Once volcanism ceases, this material is no longer building the volcano and magma in the chamber and conduit begins to crystallize. The flanks and surrounding country rock erode easily relative to the dense basalt in the conduit. Eventually the conduit, or volcanic neck, is exposed at the surface as a prominent feature.

Mineral Groups

Recall: only eight elements comprise the bulk of the rock-forming minerals, and represent over 98% (by weight) of the continental crust the two most abundant elements-silicon & oxygen-comprise nearly 3/4 of the Earth's continental crust silicon & oxygen combine to form the framework of the most common mineral group: the silicates

Hardness describes the minerals

Resistance to being scratched

Choose the most likely scenario for how this rock formed. You can infer the environmental conditions where the rock formed from the characteristics of the clasts. For example, in places where sediments are affected by high-energy waves or wind, clasts will all be weathered to a similar size and thus are well sorted. In places with quiet, calm water, small clasts like mud are most likely to accumulate in thin layers.

Rocks eroded from mountains were deposited over a short time in a dry environment, where they were buried by other sediments and cemented into rock.

porosity and permeability

Rocks with tightly packed grains and little connectivity between pores are said to have a low porosity and permeability. These characteristics of sedimentary rocks are considered when a location is being examined for natural resource extraction.

How does rock within Earth change as S waves pass?

Rocks within Earth are displaced up and down as S waves pass.

How do rocks within Earth change as P waves pass?

Rocks within Earth both expand and contract as P waves pass.

Pahoehoe is a type of lava exhibiting a ropy smooth texture on the surface. It is created from the differences in the cooling rate between the surface and the interior of the lava flow. As the hot fluid interior of the flow moves, the slightly cooled exterior bunches up and pahoehoe is formed. Look at the pahoehoe below. In which direction was the lava moving?

Ropes bend in the direction of flow (wherever they bend=flow) )))))))))))) <-- right to left

Which of the following types of seismic body waves travels only through solids?

S waves

How are S waves and vertical surface waves different?

S waves are body waves, whereas vertical surface waves are surface waves. The amplitude of S waves does not decrease with depth, but the amplitude of vertical surface waves does decrease with depth.

Most igneous rocks are primarily composed of

Silicate Materials! Silicate minerals are the most common minerals in Earth's crust and therefore make up the bulk of most igneous rocks, though minerals from many other important groups may also be present.

Which of the following geologic processes and/or phenomena is not found at transform plate boundaries?

Volcanoes

The formation of sedimentary rocks occurs under what conditions?

Sedimentary rocks form when weathered particles are cemented and/or compacted.

Which of the following motions best describes the movement of S waves as they travel through rocks following the release of energy during an earthquake?

Shaking particles at right angles to the direction of travel

Shale

Shale - comprised of silt- and clay-sized sediments very fine-grained; individual particles can't be identified without magnificaton account for over 1/2 of all sedimentary rocks deposition occurs in a low-velocity environment (lakes, river floodplains, lagoons, the deep-ocean basins) fossils are relatively common clay packs tightly in layers (laminae), which allows for poor cementation and a "weak" rock because shale packs tightly, it often forms a barrier to water/oil and gas shale does not produce prominent outcrops mudstone and siltstone

What information do geologists use to classify volcanoes?

Shape and type of deposits

Types of volcanoes?

Shield volcano Composite volcano Cinder Cone

What type of volcanoes are the tallest?

Shield volcanoes

Which of the following is not evidence supporting the theory of plate tectonics?

Shifting plates were caused by changes in the Moon's orbit.

Which two elements are found in all silicate minerals?

Silicon and oxygen

What process is evident at oceanic trenches?

Sinking of oceanic lithosphere into the mantle at a subduction zone

To fully understand the new epoch we are living in, it is useful to compare it to past epochs and consider how human activity is shaping Earth. Sort the events below based on whether they occurred before or during the Anthropocene.

Sixty-six million years ago, when dinosaurs went extinct, Earth was in the late epoch of the Cretaceous period, part of the Mesozoic era. Even further back, 3.6 billion years ago, the first oxygen-producing bacteria evolved. These events both took place long before the beginning of the Anthropocene. During the Anthropocene, the black rhinoceros become extinct, dams and roads altered Earth's drainage patterns, and atmospheric CO2 rapidly increased.

Specific Gravity

Specific gravity is a unitless number representing the ratio of a mineral's weight to the weight of an equal volume of water. Gold has a specific gravity of approximately 20.00. Quartz has a specific gravity of 2.65. Water is the standard for specific gravity at 1.00. Woods vary in specific gravity; they usually are less than water, and thus float.

Specific Gravity

Specific gravity is used to describe the density of minerals. The specific gravity of a mineral indicates its weight as compared to water. Water is used as the comparison because it is something we are familiar with. Water is assigned a specific gravity of one, and other materials are compared to that. For example, if a mineral were twice as dense as water, its specific gravity would be two. If you had a gallon of that mineral, it would weigh as much as two gallons of water. (A gallon of water weighs about 8 pounds, so the mineral would weigh 16 pounds.)

What are the two primary types of waves generated by earthquakes?

Surface & body waves

What do we call seismic waves that are transmitted along the outside of Earth?

Surface waves

Which type of seismic waves generally cause the most structural damage as they travel through Earth?

Surface waves

Which of the following correctly compares the seismograph readings from Station 1 to Station 2, as shown in the video?

Surface waves show smaller amplitude at Station 2.

Earth's lithospheric plates are composed of crust and which of the following layers?

THE OUTERMOST PORTION OF THE MANTLE

Earths structure

The Earth's surface is continuously being altered these alterations are the result of two kinds of processes: "endogenic" & "exogenic" "endogenic" - processes inside the Earth that produce flows of heat and mass, resulting from radioactive decay - the Earth's surface moves, warps, & breaks (earthquakes & volcanoes) - tend to build surface features "exogenic" - processes at the Earth's surface & in the atmosphere (external processes); involve the movement of air, water, & ice; they shape & move the landscape - tend to reduce surface features

Why are the sedimentary layers at Capitol Reef tilted?

The Laramide Orogeny is responsible for tipping the strata on their sides.

Atomic Structure-

The Nucleus: contains 99.9% of an atom's mass. It is comprised primarily of protons and neutrons. - Protons: have a positive electrical charge of +1; and weigh roughly the same as neutrons. (The # of protons that an atom has determines its atomic #.) - Neutrons: no electric charge. Contribute to an atom's mass. In most atoms there are approximately equal #s of protons and neutrons. Atoms with nuclei that contain different #s of neutrons are called isotopes. (E.g., carbon 14, carbon 12 Electrons: discrete carriers of negative electric charge that orbit the nucleus. They are not very massive (1/860th of a proton or a neutron.) Moving around the nucleus in various "orbits" (called shells or energy levels) are a cloud of light, negatively charged electrons. electrons can orbit only in certain well-defined paths, and can never be found anywhere else. Each orbital has a certain specific amount of energy associated with it; so the energy of atomic electrons can only have certain exact, specified values. Electrons move from one orbital to another by means of a "quantum leap". An electron moving to an orbital farther from the nucleus must take in energy (by absorbing light or colliding with another atom). Conversely, an electron moving to an orbital closer to the nucleus must give-up energy by emitting electromagnetic radiation.

Which of the following lithospheric plates is not included among the seven largest?

The Philippine Plate

From what you learned in the video, compare the Pleistocene climate to present-day climate of the western United States.

The Pleistocene was wetter and cooler relative to present-day climate.

Which of the following best describes the term streak

The color of a powdered form of middle produced by rubbing it across the hard surface

Volcanoes and tectonic plates

The distribution of volcanic activities across the globe often follows a regular pattern. The most active volcanoes of the world are found along the margins of oceans (oceanic-continental margins), especially within the circum-Pacific belt known as the Ring of Fire. Volcanoes found are mostly composite in nature, a notable example being Mt. St. Helens, Washington. Another set is mostly shield volcanoes that form in the deep ocean basins; for example, the Hawaiian Islands. A third group is randomly distributed volcanoes on continents, as for example, Mt. Kilimanjaro, Tanzania. Until recently, geologists had no answers for the regular pattern of volcanoes along oceanic margins and the random continental distribution. The development of the theory of plate tectonics, however, revealed the reasoning behind the pattern - plate motions provide the mechanism by which mantle rocks melt to generate magma that is erupted during volcanic eruption. Volcanism occurs along two major plate margins: convergent, where subduction of denser ocean crust under continental plates results in deep mantle melting and upward movement of magma to the surface to form volcanic arcs, and divergent plate boundaries. Here, the pulling apart of oceanic lithospheric plates through sea floor spreading causes melting (decompression melting), and eruption of the magma and the creation of volcanoes on the seafloor. In some instances, divergent plates can pull apart continental lithospheric plates, rifting continental margins and producing volcanoes.

Why are shield volcanoes wider than composite volcanoes?

The lava that flows out of shield volcanoes is more fluid than the lava that flows out of composite volcanoes.

When oceanic crust is subducted beneath continental crust, partial melting can occur. Which of the following best explains why the resultant magma rises through the crust toward the surface?

The magma is less dense than the surrounding solid rock.

Which layer of Earth possesses the greatest thickness?

The mantle is the thickest layer of Earth and contains 82 percent of Earth's volume.

sedimentary rock

The names given to clastic sedimentary rocks are, in large part, determined by the physical characteristics of the particle size rocks' clasts. Mud-sized clasts are very small, less than 0.06 mm in diameter. Sand grains are between 0.06 and 2 mm. Gravel (granule) has a larger range, from 2-4 mm. Pebbles are 4 to 64 mm. Cobbles are 64 to 256 mm. Clasts larger than cobbles are classified as boulders. Clastic sedimentary rocks can also be identified by the characteristic of clast sorting. If most of a rock's clasts fall within only one or two of the particle size classes above, the grains of the rock are said to be well sorted.

What evidence did the Deep Sea Drilling Project find about the dates of rocks in the ocean basins?

The ocean basins are relatively young; most ocean basin rocks and sediments are Cretaceous or younger in age.

At a divergent boundary, what is the relative motion of the plates on each side of the boundary?

The plates move away from each other

At a convergent boundary, what is the relative motion of plates on each side of the boundary?

The plates move toward each other

Refer to the periodic table of the elements to help you answer this question. If the number of protons in an electrically neutral atom is 92 and its mass number is 238, what is the name of that element, its number of electrons, and number of neutrons?

Uranium, 92 electrons and 146 neutrons As you can see above, the mass number, which is the atomic weight of an element rounded up, is equal to the number of protons plus the number of neutrons in an atom. The chemical nature of the atom—the element it represents—is determined by the number of protons it has.

When moving away from a divergent boundary in either direction, which of the following statements is true?

The rocks increase in age

Which of the following best describes mineral habit?

The shape a mineral grows into, given sufficient space.

As oceanic crust is subducted, it melts, forming a body of magma. When this magma rises and interacts with the overlying continental crust, what change occurs in the composition of the magma?

The silica content of the magma increases.

"metamorphic rock

The third and final major rock type that I discuss occurs when pre-existing rock is heated and squeezed, and thus deformed into a new and altered rock.

Why does quartzite not exhibit foliated texture?

There are very few or no tabular minerals in quartzite. Foliation doesn't occur in quartzite because there are very few or no tabular minerals in the parent rock.

The formation of the Himalaya and the Tibetan Plateau was caused by which of the following events?

There was a collision of two pieces of continental crust at a subduction zone.

Which of the following best characterizes ferromagnesian silicates?

They are black to dark-green silicate minerals that contain iron and magnesium.

Which of the following properly describes Mount St. Helens and the other Cascade volcanoes?

They are young, active volcanoes built on a continental margin above a sinking slab of oceanic lithosphere

Most igneous rocks never reach the surface. However, igneous rocks other than those formed in volcanoes are found exposed on many parts of Earth. How do you account for this phenomenon?

They formed at depth and have been exposed by uplift and erosion.

Which of the following paleoclimatic evidence supports the idea of the late Paleozoic supercontinent in the Southern Hemisphere?

Tillites (rocks formed by glaciers) in South Africa and South America

Other than space, what two additional factors are significant for a crystal to attain habit?

Time and necessary elements

Tsunamis

Tsunamis are large (near-shoreline) waves created by the vertical displacement along a fault located on the ocean floor. They can also be generated by underwater and near-shoreline, earthquake generated landslides.

Wave Types

Two main types of waves: "surface waves" - travel along the Earth's outer layer; and "body waves", which travel through the Earth's interior

Hornblende has ____ cleavage planes at____ angles

Two, non-90 degrees

2) Tsunamis characteristics and movement

Very long wavelengths (60 miles) Travel faster in open water - 435 mph Wave height increases as it approaches shore -- to 30 feet. (In the open ocean, wave height is not large.)

Which two scientists proved that a symmetrical magnetic pattern existed in seafloor basalts and related those stripes to spreading at a mid-oceanic ridge?

Vine and Matthews

Why are volcanoes NOT found at transform boundaries?

Volcanoes are not found at transform boundaries because they do not cause changes to the pressure, temperature, or composition of the mantle.

(3) Tsunami Damage

Wave height is related to the magnitude of the quake (direct relationship), depth of its focus, and offshore topography.

categorize igneous rocks

We also categorize igneous rocks on the basis of texture (i.e., crystal size). Crystal size is determined by how quickly the magma cools. And how quickly a magma cools is determined by where it cools in the Earth's interior. It is interesting to note that igneous rocks can have the identical mineral composition, but a very different appearance because of how quickly the magma cooled. A great example of this is seen in the igneous rocks granite and rhyolite.

.....Fossil Evidence....

Wegner documented cases of several fossil organisms that had been found on different landmasses but could not have crossed the present-day oceans which separate the continents E.g., Mesosaurus - a "snaggle-toothed" aquatic reptile whose fossil remains are limited to eastern South America and southern Africa - why not found elsewhere if it could swim?

What does the term aeolian mean?

Wind-Borne origin

While working in the field, you discover an outcrop of metamorphic rocks. What can you conclude from this observation?

You know that these rocks formed at great depth below the surface.

The Moho

Yugoslavian seismologist, Andrija Mohorovicic in 1909 presented the first convincing evidence for layering within Earth From seismic records, he found that the velocity of seismic waves increases abruptly below ~ 50 km depth - this boundary separates the crust from the mantle - the "Moho"

Igneous Rocks

a "rock" - an assemblage of minerals bound together - thousands of rock types recall: the silicates, by far, are the most common mineral group in the earth's crust most igneous rocks contain some silica (SiO2 ) ...... ~70% in granitic rocks....... ~50% in basaltic rocks ...... all rocks form from one of the following 3 processes: igneous, sedimentary, andmetamorphic processes

Alfred Wegner

a German meteorologist, in the early 1900s proposed the idea that the continents move, or "drift" as he phrased it. His ideas, however, were not accepted during his lifetime because he could not identify the processes responsible for the movement of the continents.

Currently the Juan de Fuca plate is interacting with the North American plate where inland volcanoes and deep focus earthquakes are occurring. What type of plate boundary is this?

a convergent plate boundary

The mineral fluorite is an example of:

a halide mineral.

(1) Effusive Eruptions

a relatively gentle eruption produce enormous amounts of lava characterized by low viscosity, basaltic magma (< 50% silica - thus, mafic); magma has a low gas content - gas readily escapes not explosive, thus little tephra as gases expand, jets of lava shoot upward effusive eruptions typically form "shield volcanoes" - a symmetrical mountain landform; gently sloped, gradually rising from the surrounding landscape to a summit crater - typical of the Hawaiian Islands (e.g., Mauna Loa) in rift areas - effusive eruptions send magma up through elongated fissures to the surface where it spreads out in vast sheets - e.g., the Columbia Plateau in the N.W. U.S. - "plateau basalts"

Igneous Rock Types

a single magma produces rocks with varying mineral content as magma cools, minerals with higher melting points crystallize before minerals with lower melting points as crystallization proceeds, the composition of the liquid magma changes, as the minerals rich in Ca, Fe, and Mg crystallize out of the magma the remaining liquid magma is rich in Al, Na, and K toward the end, the magma is enriched in silica additionally, there is interaction between the the solid component (crystals) and the melt - hence: "Bowen's Rxn Series"

Plate tectonics

a theory that revolutionized the discipline of Geology. Plate tectonics helps explains mountain building, earthquakes, volcanic eruptions, why continents are spreading apart, coming together, and a host of other important processes and features that we find within, and on, Earth. And the theory of plate tectonics is a relatively new idea!

True about andesite and basalt

a. cinder cones can be comprised of either andesite or basaltic magma b. basalt has more iron and magnesium than andesite c. andesite and basalt are extrusive igneous rocks d. andesite has more silica than basalt

Basaltic Type

according to Bowen's Reaction Series, the first minerals to crystallize are Ca feldspar, pyroxene, and olivine - the dark (ferromagnesian silicates) "Ultramafic" Igneous Rocks: - peridotite (intrusive) - rarely observed at the Earth's surface - comprised of mostly olivine and pyroxene - komatiite (extrusive) - rare "Mafic" Igneous Rocks: - basalt (extrusive) - pyroxene and Ca Feldspar, smaller amounts of olivine; dark green to black, fine grained; are porphyritic varieties; comprises: volcanic islands (Hawaii, Iceland), ocean floor, large portions of central Oregon & Washington (volcanic arcs) -gabbro - intrusive equivalent of basalt; dark green to black in color; composed of pyroxene and calcium-rich plagioclase; is not a common constituent of continental crust, but undoubtedly makes up a signifucant percentage of oceanic crust

When fine-grained tabular minerals in a rock at depth are subjected to differential stresses, they _________.

align perpendicularly to the plane in which the maximum compressive stress is applied. When differential stresses are applied to rocks that contain fine-grained tabular minerals, they cause the minerals to align perpendicularly to the direction in which the greatest stresses are applied, as space in the rock is reduced.

For a detrital sedimentary rock that contains mudcracks, you could be confident that the environment in which it formed was _____.

alternately wet and dry. Alternating wet and dry conditions would be a prime environment for the formation of mudcracks

Application of low-grade metamorphic forces to a rock causes _____.

an increase in rock density

Continued movement of the continental crust on the west side of the San Andreas fault could result in which of the following features?

an island

The East African rift is a divergent plate boundary that is splitting the continent of Africa into two pieces. What will eventually form around this divergent boundary?

an ocean

A geologist sends you a sample that was collected in the field. You find that it is a gray-colored igneous rock containing amphibole and intermediate plagioclase feldspar. Using Bowen's Reaction Series as a guide, how would you describe its composition?

andesitic Amphibole and intermediate plagioclase feldspar occur in the andesitic temperature regime.

chemical sedimentary rocks

another type of sedimentary rock where the material that forms the sedimentary rock precipitates from a water solution to form the rock.

Subduction

are areas where the more dense oceanic crust (basalt ~3.0 g/cm3 ) collides with the less dense continental crust (~2.7 g/cm3 ) the oceanic crust dives beneath the continental crust forming a "subduction zone" (oceanic trenches - "Mariana Trench" - 36,198 ft) the subducted crust is re-melted in the mantle, & then migrates back up through the crust via fissures & cracks to form volcanic mountains (e.g., Andes Mountains)

(2) Explosive Eruptions

are associated with subduction zones are violent & unpredictable eruptions the result of magma that is thicker, stickier, higher in gas content & silica (magma is more felsic) tends to produce blockages in the volcano's conduit, trapping & compressing gases - leading to higher pressures inside the volcano > explosive eruption produces the "composite volcano" landform composite volcanoes have steep sides & are more conical than shield volcanoes when the explosion takes place, the top & sides of the mountain are often blown off - less lava, lots of "pyroclastics" (explosively ejected rock fragments)

Chemical Sedimentary Rocks - Process:

are formed from material that had been dissolved into solution - important in oceanic environments this material is transported in solution & then is precipitated-out of the solution - forms "chemical sedimentary rock" e.g., limestone (CaCO3); and dolomite (CaMg(CO3)2 these sedimentary rocks can later be dissolved in solution (weathered) & assume unique structures - "Karst Landscapes" a particular class of chemical sedimentary rocks: evaporites - inorganic material that has been dissolved in solution & then is left behind when the water evaporates; e.g. gypsum & sodium chloride

Intrusive igneous rocks

are rocks that form from cooling and crystallizing magma, inside the earths crust. They are "brand new" rocks; they form as the minerals in magma cool and crystallize. Since the silicate minerals are so common in Earth's crust, the silicate minerals also are common in igneous rocks. As a matter of fact, one of the ways we classify igneous rocks is on the basis of how much silica (SiO2, which is quartz) the igneous rock contains. For example, the igneous rock granite (which is very common in continental crust) is ~70% silica, whereas, basalt (common in oceanic crust) is only ~50% silica.

Pyroclastic debris from a volcanic eruption can include _____.

ash and cinders. Along with bombs and lapilli, ash and cinders are common components of pyroclastic debris ejected from volcanoes.

Eruption Process

at the higher pressures deeper inside the Earth, gases are dissolved in the magma as the magma moves to the near-surface environment, it encounters lower pressures and the dissolved gases are released and expand the basaltic (less viscous) magma does not impede (as greatly) the movement of these gases up and outward from the near-surface environment in contrast, the very viscous granitic magmas tend to prevent the gases from escaping the near-surface environment, and pressures build... until the volcano explodes !!!! (boom) e.g., Mt. St. Helens)

What is foliation?

banding in metamorphic rocks that results from the reorientation of minerals

Which one of the following statements is NOT true about andesite and basalt?

basaltic lava is thicker than andesitic lava. This statement is not true because andesite is stickier (more viscous) than basalt. The viscosity of the andesite trapped the gas bubbles in the magma of SP Crater, leading to the vesicular texture of the andesitic lava.

Carbonates

basic building block of the carbonates is the carbonate ion. The carbonate minerals are commonly used in building materials.

What is the term used to describe a very large, widespread, and deep intrusive body of igneous rock?

batholith

Minerals must be solid, have an orderly atomic structure, have a recognized chemical composition, be naturally occurring, and __________.

be generally inorganic in origin

Where do most metamorphic rocks form?

between a few and many kilometers beneath Earth's surface

What coal is soft, black in color, and produces soot upon handling?

bituminous

(3) Break-Up of Pangaea

by 135 M.Y. ago - beginning of Cretacious - N.A. was spreading away from the landmasses to the east as new sea floor was forming in the Atlantic; India was sliding northward the leading edge of the India plate was diving under Eurasia ("subduction"); while new sea floor was forming along the trailing edge of the plate ("sea-floor spreading")

The geologic laboratory where you work received a sample for analysis that is composed of calcite that includes many microscopic fossils of marine organisms and reacts with acid. What name would identify this rock?

chalk. Chalk is a biochemical sedimentary rock composed of calcite and contains many microscopic fossils of marine organisms.

What is one way that cinder cones differ from composite and shield volcanoes?

cinder cones are smaller than composite and shield volcanoes

What is piled up along the cone of SP Crater that causes it to be so steep?

cinders

detrital (physical) sedimentary rocks

clasts get hardened and cemented together to form detrital (physical) sedimentary rocks;

Which two minerals are most common in detrital sedimentary rocks?

clay minerals and quartz. Clay minerals are the resistant by-product of chemical weathering and quartz is the most resistant common mineral in Earth's crust. They are common in detrital sedimentary rocks.

sedimentary rocks -

come from weathered pre-existing rocks &/or organic materials the weathered material has been transported, deposited, and lithified sedimentary rock accounts for 5% (by volume) of the Earth's outer 16 km sedimentary rock comprises a relatively thin, discontinuous layer in the uppermost portion of the crust 75% of all rock outcrops on the continents are comprised of sedimentary rock sedimentary rock sometimes contains evidence of past environments and of the mechanisms involved in their formation (e.g., the how the sediments were transported) many sedimentary rocks have important economic value (e.g., coal, oil & gas, fertilizers, construction material)

Contact metamorphism takes place when rocks _____.

come in contact with a magma body. When rocks come in contact with a magma body, they can be altered by contact metamorphism.

Lithification of Sedimentary Rocks

compaction & cementation work hand-in-hand (compaction and cementation = lithification) cementing materials: silica, calcite, iron oxide

What is the classification of igneous rocks based on?

composition and texture. Composition is determined by the minerals in the rock and texture relates to the grain size. This is the basis of the classification of igneous rocks.

What best describes the movement of P waves?

compression and expansion

Working in the field, you find a rock that contains rounded fragments that are greater than 2 mm in diameter. What would you call this rock?

conglomerate. Conglomerate is a detrital sedimentary rock that is characterized by rounded fragments that are larger than 2 mm in diameter.

What process forms igneous rocks?

cooling and solidification of magma

Conglomerate or Breccia:

conglomerates consist largely of gravels particles range in size from large boulders to pea-size conglomerates are poorly sorted (because they often contain sand and mud sized particles as well) are deposited in turbulent (mountain) streams and areas of strong wave action; are found in association with landslides and glacial activity as well if the large pieces in the rock are angular, the rock is called "breccia" - indicates that little transport of the sediment took place

Cinder cones are characterized by explosive eruptions where pyroclastic material is ejected and builds on the flanks. Basaltic lava flows are formed during effusive eruptions of lava and pyroclastic material us usually ejected during explosive erruptions. Pahoehoe is lava with a ropy texture commonly found on the lava flow surface. Both cinder cones and lava flows are composed of extrusive igneous rocks.

cool

Other facts about upper mantle

crust" - .01% of Earth's mass "crust" + "high velocity zone" = "lithosphere" the boundary or discontinuity between the crust and the high velocity zone below, is referred to as the "Mohorovicic Discontinuity" (Moho) crust below mountains - 50-60 km depth crust below continental interiors - ~ 30 km depth - comprised of granite crust below oceans - ~ 5 km depth - comprised of basalt

Magma Crystallization

crystallization (defn) - the formation and growth of a crystalline solid from a liquid or gas magma - a body of molten rock found at depth; the liquid portion is comprised of freely moving ions; it may also contain suspended crystals and dissolved gases

(1) The crystallization process:

crystallization is the opposite of melting as the magma cools, the ions in the magma lose kinetic energy, and occupy less space with sufficient cooling (loss of KE) the electrostatic forces between ions will begin to "glue" bond the ions together into an orderly crystalline structure centers of crystal growth - "embryo crystals" - exist throughout the the magma with slow cooling, have just a few centers of growth, yields larger crystals with quick cooling, lots of centers of growth competing for ions, thus, have a small (sometimes microscopic) crystals if the magma cools very quickly, there is insufficient time for the ions to arrange themselves in a crystalline structure = volcanic glass = randomly distributed ions

Plate Tectonics

defn: refers to large-scale movement and deformation of Earth's crust

Igneous Rock Textures

describes the overall appearance of the rock - based on size and arrangement of the crystals texture is determined predominantly by the cooling rate of the magma o aphanitic, phaneritic, porphyritic (phenocrysts & groundmass), glassy, pyroclasts

What is a coarse-grained rock composed of intermediate plagioclase feldspar and pyroxene?

diorite. Diorite is a coarse-grained rock with intermediate plagioclase feldspar and pyroxene.

Which processes result in mineral flattening during metamorphism?

dissolution followed by crystallization

Magma Composition Magma Temperature Amount of Dissolved Gases

each of these affects the magma's "viscosity" - the magma's resistance to flow

Rock salt is an example of a(n) __________, deposited by saturation and precipitation in evaporating water.

evaporite

When lava erupts at Earth's surface, what type of rock is produced?

extrusive. Magma that reaches the surface cools quickly, has fine-grained texture, and produces extrusive rocks.

Working in the field, you see a thin, dark-colored igneous sill across the valley. Without seeing the sill up close, what texture would you expect it to possess?

fine-grained. Because rock is a relatively poor conductor of heat, smaller intrusions would tend to cool more quickly than large intrusions.

"extrusive" igneous rocks

form at the surface of the earth(e.g., volcanoes).

(4) Pyroclastic Rocks

form from fragments ejected during volcanic eruptions tuff - composed of ash-sized fragment breccia - composed of particles larger than ash

Evaporites

form when evaporation is the mechanism triggering precipitation e.g.'s,: halite (NaCl), gypsum (plaster) (CaSO4), the mineral sylvite (potash) (used as a fertilizer)

What is the most efficient agent of metamorphism?

heat. because it provides the energy to drive reactions.

(2) Andesitic (intermediate) Type

found near the middle of Bowen's Reaction Series has a mineral composition between that of basalt and granite - amphiboles and plagioclase feldspars - andesite (extrusive) - fine-grained, medium gray in color, comprises many volcanoes (Andes Mountains) - common as a porphyry - diorite (intrusive) - coarse-grained, appearance similar to that of granite; distinguished from granite by the absence of quartz crystals - light colored feldspars and dark amphibole crystals yield "salt & pepper" appearance

Which environment of deposition is NOT represented by the rocks in Capitol Reef National Park?

glacial. None of the sedimentary rock layers in Capitol Reef National Park were deposited during a glacial episode.

What would you call a granite that has undergone metamorphism and now exhibits foliation?

gneiss

What do we call a metamorphic rock that has coarse-grained texture, minimal amounts of mica, and contains minerals that are segregated into bands?

gneiss.

What property of detrital sedimentary rocks can be indicative of the energy of sediment transport?

grain size. Grain size in a detrital sedimentary rock typically indicates the amount of energy associated with the transport of the sediment. High-energy transport can move much larger grains than low-energy transport.

(1) Subduction-Zone Volcanism

heat from radioactive decay in the crust & mantle melts subducting oceanic crust, forming basaltic-andesitic magma, which moves upward (less dense) and: *** when it occurs in an ocean, it can produce a chain of volcanoes - "Island Arcs" (e.g., Aleutian Islands) ***when it occurs beneath continents, the magma assimilates silica-rich crustal material, forming a granitic-andesitic magma (e.g., Andes Mountains of South America) Volcanoes that ring the Pacific ("Ring of Fire") are associated with subducted oceanic crust that contains abundant water (which lowers the melting point of rock); the resultant magma has a high water vapor content, which leads to "explosive" volcanoes - such as those of the Cascade Range in the Northwestern U.S. (eg., Mt. St. Helens)

An igneous rock that contains quartz and potassium feldspar would have a mineralogic content placing it in the range of __________.

granitic or felsic rocks

What mineral is the major component of rock salt?

halite

Amongst all seismic waves, surface waves _____

have the slowest velocity.

(1) Magma temperature

heating makes the magma less viscous (more fluid); as the magma cools it congeals and its mobility decreases

A very long-lived magma source located deep in the mantle is called a(n) __________.

hot spot

The ratio of silicon to oxygen atoms in silicate minerals depends on:

how the atoms in silicon-oxygen tetrahedra are shared.

What agent might metamorphose rocks found adjacent to a large magma body?

hydrothermal solutions. Hydrothermal solutions are the most influential factor inducing metamorphism to take place in rocks adjacent to a magma body.

What is the basic foundation of moh's hardness scale?

if a mineral scratches an object then the mineral is harder in the object

....Rock Types & Structures Match....

if continents were once joined, rocks and structures on the margins of each continent should match in terms of age and type. The Appalachians trend northeastward through the eastern U.S. and disappear off the coast of Newfoundland - comparable mountains (in age & structure) are found in the British Isles and Scandinavia

A sandstone contains inclusions of metamorphic rock. An igneous dike cuts both the sandstone and inclusions. List the rocks from youngest to oldest.

igneous dike, sandstone, metamorphic rock

Metamorphism Causes:

increased density growth of larger crystals foliation (reorientation of the mineral grains into a layered or banded appearance) transformation of low-temperature minerals into high-temperature minerals the introduction of ions generates new minerals—some value metallic ore deposits are formed in this manner

(2) Chert

is a type of chemical sedimentary rock comprised of microcrystalline silica (or quartz) some chert is precipitated from seawater to form nodules of chert - thus it's inorganic most chert is believed however to be organic in nature - derrived from the silica-rich skeleton's of marine organisms (diatoms and radiolarians)

Coal

is different from other chemical sedimentary rocks it is comprised of large amounts of plant material that has buried - initially in a swamp - an oxygen poor environment, which limited decomposition high temperatures and pressures drove-off volatiles and changed the plant material to > peat > lignite > bituminous > anthracite (metamorphic rock)

Why does magma have a tendency to rise after its formation?

it is less dense than the surrounding rock. As rock melts, the density decreases. This process causes the magma to rise.

All of the following criteria define a mineral except:

it is not organic (These are true: it is inorganic. It is naturally occurring. It has a well-defined chemical composition. It has an orderly internal structure.)

FActs

it's important to keep in mind is that it's the interactions between the electrons of atoms and ions that are responsible for bonding elements together to form minerals.

The external expression of a mineral's orderly internal arrangement of atoms is referred to as:

its crystal form.

What is the most abundant chemical sedimentary rock in Earth's crust?

limestone. Limestone is composed of calcite and is the most abundant chemical sedimentary rock in Earth's crust.

earth's internal structure is the

lithosphere (which is comprised of crust plus high velocity zone) forms a rigid layer that sits atop the asthenosphere. This fact plays a key role in the movement of Earth's great lithospheric plates, and is an important component of plate tectonics—

Abundant plant material accumulating in a swampy environment with __________ is required for peat to form.

low oxygen levels

The amount or quality of light that is reflected from a mineral surface is known as __________.

luster

Factors Affecting the Eruption:

magma chemistry magma viscosity (resistance to flow)

Gas Content of Magmas

make-up 1-6% of magmas (by weight) thousands of tons/day water vapor is greatest constituent outgassing of water vapor formed oceans Hawaiian Volcanoes: 70% water vapor; 15% carbon dioxide; 5% Nitrogen; 5% Sulfur > Sulfuric Acid Gases propel magma & create conduits for their escape to the surface - connect magma chamber to the surface

(2) Common Nonfoliated Rocks

marble - a coarse, crystalline rock; the parent rock is limestone. Marble is composed of large interlocking calcite crystals, formed from the recrystallization of smaller grains in the parent rock (limestone) quartzite - a very hard metamorphic rock formed from quartz sandstone - formed under moderate-to-high-grade metamorphism. The quartz grains in the sandstone are fused together

The property of cleavage reflects:

mechanical breakage along planes of weakness within the mineral.

Which two rock types would you expect to see sitting next to each other after a very long period characterized by only uplift and erosion?

metamorphic and sedimentary rocks

How is anthracite produced from bituminous coal?

metamorphism

What do we call a metamorphic rock that has a coarse-grained texture, is dominated by mica, and contains no other notable minerals?

mica schist. A metamorphic rock dominated by mica and with a coarse-grained texture is classified as schist.

Plate Tectonics and Volcanic Activity

most active volcanoes are associated with plate boundaries - spreading center, subduction zone, intraplate Earth's ~ 600 active volcanoes are predominately near convergent plate boundaries

Magma Composition

most magma is comprised of 8 elements: Si, O, Al, Na, K, Ca, Fe, & Mg makeup the silicate minerals also find trace amounts of other elements, plus volatiles volatiles - materials that are gases at surface temps and pressures - e.g., water & CO2 - visicles - e.g., the rock scoria the minerals are not all formed at the same time - some minerals crystallize at higher temperatures than others

Minerals are:

naturally occurring inorganic a solid have an orderly internal structure have a definite chemical composition and have unique properties that make them different from the elements that comprise them rocks - a mixture of minerals, with each mineral retaining its own identity

Which of the following igneous rocks contains no mineral crystals?

obsidian. Obsidian cools so quickly that the individual ions in the lava do not have time to organize into a crystalline structure.

(2) Intraplate Volcanism

occurs in the middle of continental and oceanic plates (perhaps where the plates have been stretched/weakened) most likely the source is the partial melting of mantle rocks the basaltic magma may come from rising plumes of hot mantle material (e.g., Hawaii, Columbia Plateau basalts) or, when the extruded lavas are granitic in composition, silica rich continental crust may have been melted/incorportated in the rising plumes of basaltic magma from the mantle (e.g., Yellowstone region)

Faulting

occurs when rock strata are strained beyond ability to remain as one solid unit they fracture & one side of the fault is displaced relative to the other side at the moment the fault line shifts, there is an intense release of energy (an earthquake)

(Locations of Volcanic Activity) (1) Along subduction boundaries

oceanic plate - cont. plate (e.g., Mt. St. Helens) oceanic plate - oceanic plate (e.g., Japan)

(3) Spreading Center Volcanism

oceanic spreading centers produce the greatest volume of volcanic rock as the lithosphere pulls apart, the pressure on the underlying rocks is reduced, lowering the melting point of the mantle rocks (peridotite), and producing large quantities of basaltic magma, which moves upward through the cracks and fissures to the ocean floor and spreads out, or builds a volcanic cone (e.g., Surtsey) spreading center volcanism can also occur on continents - e.g., African Rift Zone

Sea-Floor Spreading

on the sea floor there exists an interconnected worldwide mountain chain - 64,000 km long & 1,000 km wide - called "mid-ocean ridges" they result from upwelling flows of magma from hot areas in the upper mantle & asthenosphere mantle convection brings the material to the crust, the crust is fractured & the magma cools to form new sea floor the youngest crust is near the ridges; the crust gets older w/increasing distance from the ridge

The silicon-oxygen tetrahedron contains:

one silicon atom and four oxygen atoms.

Earth's Geosphere

or solid earth

How will minerals orient when a rock is put under shear stress?

parallel to the direction of the shear stress

Name the progression of coal types with increased heat and pressure from burial.

peat, lignite, bituminous, anthracite

How will foliation in continental metamorphic rocks formed during subduction be oriented?

perpendicular to the direction of plate movement

How will minerals grow when a rock is put under normal stress?

perpendicular to the direction of the greatest stress

How will minerals orient when a rock is put under normal stress?

perpendicular to the direction of the greatest stress

In addition to temperature, which of the following agents increases with depth in Earth?

pressure. Pressure on rock increases with depth and, along with temperature, is influential in metamorphism.

Occurrence of Earthquakes

principal zones of earthquake activity occur near plate boundaries: o convergent, divergent, transform, intraplate (basin & range, midcontinent)

An undeformed sequence of sedimentary rocks is exposed in a large river canyon. Which two principles would be demonstrated by the rocks?

principles of superposition and lateral continuity

(1) Heat

probably the most important agent of metamorphism it provides the energy to recrystallize minerals Heat Source: o rocks near the surface are heated greatly when they are intruded by magmas originating at depth o or, when surface rocks are buried - recall the thermal gradient (20-30 degrees C/km)—e.g., clay becomes unstable and recrystallizes to minerals that are stable at these higher temperatures (e.g., muscovite)

A. Continental Drift

proposed by Alfred Wegner (1915) - the idea that the continents migrate (we now know that the continents do move at speeds of up to 6 cm/year) all landmasses were once united in a giant "supercontinent" - "pangaea" ~ 225 million years ago

Cinder cones are made of________.

pyroclastic deposits

Basalt is an igneous rock that can be identified by its small crystals. What are they composed of?

pyroxene and calcium-rich plagioclase feldspar. Basalt is a mafic fine-grained igneous rock that contains pyroxene and calcium-rich plagioclase feldspar.

The principal mineral used in making glass is:

quartz

(2) Pressure

recall that pressure also increases with depth as parent rocks are buried, they are subjected to force by the overlying material—"confining pressure"—this force is applied equally in all directions—rocks deform by decreasing in volume in addition to the pressure applied by the load of the material above, stress exerted during mountain building—"directional stress" (a vice-like stress)—shortens and deforms rock stratao it creates intricate bends (folds)—recall that rock behaves in a plastic manner at depth.

Earths internal structure

recall that the Earth is thought to have formed from a cloud of gas & dust (a nebula) ~ 4.6 billion years ago as the Earth became compacted, heat accumulated in its interior (heat was also added via radioactive decay) under the force of gravity, the heavier elements sank & the lighter elements rose toward the surface the Earth's interior is arranged in concentric layers - & each layer is differentiated by heat/chemistry heat moves outward via conduction & convection the Earth's internal structure has been determined on the basis of indirect evidence - "seismic evidence" [seismic waves (shock waves) pass through different materials in different ways and at differing speeds] earth's core - 1/3 of Earth's mass; 1/6 of it's volume "inner core" - composed of solid iron (Fe); density = 13.5g/cm3; its solid because of very high pressures "outer core" - is molton iron; density ~ 10.7 g/cm3 outer (liquid) core is responsible for ~ 90% of Earth's magnetic field (hypothesis: circulation in the outer core produces currents which in turn induce the Earth's magnetic field) "mantle" - 80% of the Earth's total volume; density ~ 4.5 g/cm3 is separated from the outer core by the "Gutenberg Discontinuity" (discontinuity: a place with a change in physical properties) density decreases as you go up in the mantle the mantle's temperature increases gradually with depth there are two divisions to the mantle, an upper mantle & a lower mantle

At a mid-ocean spreading center, alteration of rocks by chemically active fluids causes metamorphism by __________.

replacement or substitution of ions in the pre-existing rock. Metamorphism of rocks at a mid-ocean spreading center by chemically active fluids causes metamorphism by the replacement or substitution of ions in the pre-existing rocks.

What is a fine-grained igneous rock composed primarily of very small crystals of potassium feldspar and a few large crystals of quartz?

rhyolite porphyry. This rock is of a felsic (rhyolitic) composition with a porphyritic texture.

Which type of magma has the highest viscosity?

rhyolitic. In general, the higher the silica content of a magma or lava, the greater its viscosity, or resistance to flow.

Which structure is common in sedimentary rock?

ripple marks, mud cracks, cross-bedding, fossils are all features found in sedimentary depositional environments.

Which is an example of a sedimentary rock composed of solid masses of intergrown crystals?

rock salt. Rock salt is a sedimentary rock that contains intergrown crystals of halite.

clasts

rocks that were once already rocks, and may be, as an example, comprised of small sediments.

Which of the following agents is capable of moving sediment from the site of formation to the site of deposition?

running water, wind, ice, waves

In your field area you find a quartz sandstone unit with cross-bedding in it that is on the order of 2 m high. In what environment would you deduce this rock formed?

sand dunes. Quartz sandstone with 2-meter-scale cross-bedding would be typical of sand dunes.

We now know that the continents are pushed apart at

sea floor spreading centers, and sea floor is destroyed at subduction zones.

Sandstone

sedimentary rocks in which sand-sized grains predominate accounts for 20% of sedimentary rocks quartz ("quartz" sandstone) (because of its durability) is the predominant mineral in most sandstones the degree of similarity in grain size - "sorting" - tells us about the depositing environment; well sorted vs. poorly sorted windblown deposits are typically better sorted than are deposits resulting form wave action; and wave action sorts better than stream action streams, waves, and wind tend to round the particles; and very rounded particles imply that long-distance transport took place conversely, angular grains indicate that the material was transported a short distance, and by some other medium (e.g., ice)

Basic Principles

seismic waves are "elastic energy" as rock is deformed it bends, storing elastic energy once the rock is strained beyond its breaking point it ruptures releasing the stored-up energy in the form of earthquake waves the waves occur as the rock elastically returns to its original shape the wave (energy) radiates outward form the focus in all directions

Igneous Structures:

shape relative to the host rock: a) tabular - igneous body has a flat shape (b) massive - large and somewhat irregularly shaped discordant - cut across existing structures concordant - form parallel to existing structures a "pluton" - any intrusive igneous structure a "batholith" - the largest form of a pluton - an irregular shaped mass with a surface exposure > 100 km2 - they form the mass of many large mountain ranges "sills" - plutons that form parallel to layers of sedimentary rocks - tabular and generally concordant - less viscous magma "dikes" - plutons that cross layers of country rock - discordant and tabular - are injected into fractures in country rock - more viscous fluid "laccoliths" - lens-shaped plutons in country rock - generally concordant - more viscous magma, lifts (arches) overlying strata all of these intrusive structures can be exposed by the weathering actions of air water, & ice

Crystallization Environment

silicate minerals crystallize as the magma cools if it cools near Earth's surface = low temp & pressure environment if the magma cools at depth = high temp & pressure environment the environment during crystallization & the chemical composition of the magma determine which minerals are generated quartz = low temps (so we say that quartz is a "low temperature" mineral) olivine = high temps (so we say that olivine is a "high temperature" mineral) thus, mineral structure and composition is indicative of the conditions that existed when the mineral was forming tells geologists about the environment where the minerals formed

What is the primary type of mining that takes place under the Bolivian mountain, Cerro Rico?

silver

(1) Common Foliated Rocks

slate - a very fine-grained foliated rock comprised of minute mica flakes - (the clay minerals that comprised shale were recrystallized into fine grained mica flakes) - because the mica flakes are so small, the foliation isn't visible schists - strongly foliated rocks, formed by regional metamorphism; they tend to be "platy", and can be split into thin flakes or slabs; the parent material for schist is shale; the term "schist" refers to texture and not composition - e.g., schists comprised of mica, are called "mica schists" gneiss - a term applied to banded metamorphic rocks; they are formed from high-grade metamorphism; they contain elongated and granular (not platy) minerals they exhibit a strong segregation of the light and dark silicates (most common minerals are quartz and feldspar); they can be deformed into intricate folds

What do we call a metamorphic rock that has microscopic to very fine-grained texture, breaks into slabs or sheets and is dull on the surface?

slate. A metamorphic rock that has very fine-grained texture and slaty cleavage would be identified as slate.

In the United States, the most common type of coal is __________ and the largest producing state is __________.

sub-bituminous; Wyoming

Do metamorphic rocks look like the preexisting rock from which they form?

sometimes, but not always

What is rock texture?

the way a rock looks

Sedimentary Structures

strata (beds) - sedimentary rocks are laid down in layers bedding planes - a nearly flat surface separating two beds of sedimentary rock; each plane marks the end of one deposit and the beginning of another having different characteristics cross bedding - when sediments do not accumulate in a horizontal fashion fossils, ripple marks, mud cracks - provide clues to past environments

Which of the following has the single most immediate effect on lava's ability to solidify?

temperature

In addition to mineralogic composition, the degree of metamorphism in a rock is also characterized by _____.

texture. Texture refers to grain size and is used with mineralogic composition to characterize the degree of metamorphism.

(3) Granitic Type Igneous Rocks

the "Felsic" Igneous Rocks: the last minerals to crystallize from the magma are K feldspar and quartz (SiO2) Granite (intrusive) - a phaneritic rock; 25-35% quartz and > 50% K and Na feldspar, minor amounts of muscovite, biotite, and amphibole granite forms the base of many of the world's mountain ranges - Pikes Peak, Mount Rushmore (Black Hills), White Mountains, Stone Mountain (Georgia) it is very abundant and resistant to weathering - remains after sedimentary strata have eroded away Rhyolite (extrusive) - volcanic equivalent of granite; usually aphanitic - light gray to pink in color - rather uncommon compared to granite - exception, of lava flows in Yellowstone Obsidian - volcanic glass ... Pumice

When oceanic and continental crust collide at a subduction zone, one plate is forced under the other. The angle at which the subducting plate descends is due to which of the following factors?

the age of the plate being subducted the density of the plate being subducted

Crystal habit is the shape that a mineral develops by the repetition of __________.

the basic unit cell of a mineral

In silicate minerals, the type of cleavage or fracture is influenced by:

the bonding of the silicon-oxygen tetrahedra within the mineral.

The Earth's Plates (Plate Tectonics)

the crust is split-up into 14 plates (1) divergent boundaries - (e.g., sea-floor spreading centers) - upwelling mantle forms new sea floor & the plates are spread apart (e.g., East Pacific Rise between Nacza Plate& Pacific Plate) (2) convergent boundaries - where areas of continental and/or oceanic crust collide - e.g., subduction zone off western S.A., between Nazca Plate & S.A. Plate - produces mountain building & volcanism (3) transform boundaries - plates move laterally past one another - typically no associated volcanic eruptions (defn: "fault" - an area where fracturing & displacement occur between two portions of the Earth's crust) (transform fault - an elongated zone along which faulting occurs between mid-ocean ridge crests - lateral motion - no new crust formed or destroyed ** Earthquake & volcanic activity occur primarily at the plate boundaries **

Metamorphism & Textural Changes

the degree of metamorphism is reflected in the rocks texture and mineralogy when subjected to low-grade metamorphism, the parent rock becomes more compact (more dense)—e.g., shale to slate o pressure causes the clay minerals to align into a more compact arrangement when subjected to higher-grade metamorphism, pressure causes certain minerals to recrystallize—in general, recrystallization encourages the growth of larger crystals o thus, many metamorphic rocks consist of visible crystals (like phaneritic igneous rocks) o the crystals of some minerals will recrystallize with a preferred orientation—perpendicular to the direction of compression o the resulting mineral alignment gives the rock a layered/banded appearance—a foliated texture Not all metamorphic rocks have a foliated texture—"nonfoliated" texture (e.g., marble) in general, metamorphic rocks composed of only one mineral (e.g., calcite > limestone > marble), are not visibly foliated

....Magnetic reversals & seafloor spreading:

the earth's magnetic field periodically reverses polarity; ("normal"=today's; "reverse"=opposite of today's) magnetometers revealed alternating strips of seafloor having different intensities of magnetism; low intensity strips corresponded to reverse polarity; high intensity strips correspond to normal polarity provides further evidence of plate tectonics

(3) Amount of Dissolved Gases

the gas content of a magma determines its explosiveness basaltic magmas = low (1-2%) gas content andesitic magmas = intermediate (3-4%) gas content granitic magmas = high (4-6%) gas content

Today's Continental Positions

the leading edge of the India plate has pushed under the southern portion of Asia (subduction) & formed the Himalayas plate motions continue today, & will continue in the future

As a result of partial melting, magma originates in __________.

the mantle and crust. Tectonic forces act in the mantle and crust to cause rocks to melt and form magma.

....Paleomagnetism....

the most persuasive evidence for continental drift/plate tectonics comes from the study of the Earth's magnetic field recall that the Earth's magnetic field has a north pole and a south pole - which align closely with the geographic poles - (think of a giant bar magnet placed at Earth's center) invisible lines of force pass through the Earth, from one pole to the other any "freely moving" magnetized object would become aligned with these lines of force & would point toward the magnetic poles - e.g., a compass needle, which itself is magnetized some of Earth's early iron-rich minerals (found in basalts), became magnetized in the direction parallel to the Earth's existing magnetic field - once cooled, their magnetism was frozen in place - act like a compass, pointing toward the Earth's magnetic poles discovery: the magnetic alignment of these rocks possessing fossil magnetism (paleomagnetism) has changed with time two explanations: (1) the poles had wandered; or (2) the lava flows had moved over time this movement resulted from continental drift - plate tectonics

B. Evidence for Continental Drift....Fit of the Continents...

the similarity between the coastlines on opposite sides of the South Atlantic was noted by Wegner a better fit between the continents was obtained by using the edges of the continental shelf

In what type of igneous feature would you find rocks with a vesicular texture?

the surface of a lava flow. Because escape of gas from lava is possible only at or close to the surface of Earth, lava flows may possess vesicular texture.

Seismic Waves

the velocity of seismic waves depends on the density & elasticity of Earth's material - waves move with the greatest speed through rigid materials (e.g., faster through crystalline rocks than unconsolidated material) in the same layer, wave speed increases w/depth, because pressure increases and squeezes the rock into a more compact material P-waves travel through solids as well as liquids S-waves can not travel through liquids, because unlike solids, liquids have no shear strength (they simply flow) in all materials P-waves move faster than S-waves when seismic waves pass from one material to another, the wave is refracted (bent); (some energy is reflected from the discontinuity) when passing from one layer to the next waves can be: speeded-up, slowed-down, refracted, or reflected

Silicates

they are classified on the basis of how silica rich/poor and iron and magnesium rich/poor they are.

How do metamorphic rocks reach Earth's surface?

through removal of overlying rocks

The volcanic islands in the above figure were created as the tectonic plate passed over a hot spot in the mantle. Based on the ages of the volcanic islands, in what direction was the tectonic plate moving toward?

toward the west

"hydrologic cycle"

transports & deposits material

what causes vesicles to form in lava?

trapped gas bubbles

(2) Magma composition

viscosity is directly related to silica (SiO2) content: high silica = high viscosity; low silica = low viscosity magmas which produce basaltic rocks contain ~50% silica; granitic magma contains ~70% silica; andesitic magma contains ~60% magma e.g., Hawaiian volcanoes - basaltic magma - very fluid lava (can travel 150 miles)

Volcanic Landforms and Materials

volcano - a landform at the end of a conduit or pipe which rises from below the crust & vents to the surface crater - a circular surface depression formed by volcanism; usually located at a volcanic vent or pipe lava (molton rock) - the magma which issues from the volcano tephra - pulverized rock and clastic material (rock fragments) ejected violently during a volcanic eruption > 1300 volcanoes world wide; < 600 are active; 70 (mostly inactive) volcanoes along western North America cinder cone - a landform comprised of tephra & scoria (a cindery rock), usually small & cone shaped - ht. not more than 450 m (1500 ft) - a truncated top formed from cinders during the course of a moderately explosive volcano caldera - the interior sunken portion of a volcanic crater; usually steep-sided & circular - sometimes contains a lake forms when the summit material on a volcanic mountain collapses inward after an eruption

As oceanic crust is subducted below continental crust, which of the following factors most directly drives the melting that will fuel volcanoes at the surface?

water

(3) Chemically active fluids

water is trapped in the pores spaces of rock with deep burial and heating, water is forced from the pore spaces, and acts as a catalyst by aiding the movement of ions minerals recrystallize to form more stable structures; or, ion exchange among minerals creates brand new minerals—e.g., at Yellowstone, where hot mineral-rich water creates completely altered rocks in the near surface environment

The names of primary and secondary refer to _____

wave speed

B. Detrital Sedimentary Rocks - Process:

weathering & erosion of preexisting rock, generates fine-grained bits and pieces of (solid) material - "sediment" - (more specifically, "clastic sediments") this sediment is comprised mainly of quartz, feldspar, & clay minerals, & some micas these materials are then transported (by wind, water, gravity, & ice) elsewhere & deposited the sediments are laid down in horizontally layered beds -- which form strata 3("stratigraphy" - the study of the sequences, & spacing of these strata in order to determine the age and origin of the rocks) the sediments are then compacted, cemented, or hardened ("lithification") to form sedimentary rock (Note: If feldspars and micas are present in the detrital rock, it indicates that erosion and deposition took place quickly, since these minerals weather quickly) detrital rocks are classified on the basis of particle size particle size provides useful information about the deposition environment currents of air or water sort the particles by size - the stronger the current the larger the particle size carried

The formation of sedimentary rock requires _____.

weathering and erosion of pre-existing rocks. Weathering breaks down pre-existing rock into particles, while erosion moves the particles to a site of deposition. These processes begin the formation of sedimentary rock.

Isotopes & Radioactivity

while the isotopes of most elements are stable (do not decay); the isotopes of some elements do decay naturally through a process called "radioactivity" a decaying atom emits particles and energy - this occurs when the forces that bind together the nucleus are not strong enough to hold it together the rate at which a nucleus decays is steady and determinable this (along with other information about the "parent" and "daughter" material) makes radioactive isotopes useful for dating materials and geologic events

Which of the following agents move sediment from one place to another?

wind glaciers rivers

the most common family of minerals

—the silicates.

building block of the silicates

—the silicon oxygen tetrahedron, and note that it has a charge, so it's very reactive