Geology Exam 1

Systems can be open or closed

Open- both energy and matter can enter or leave the system Closed- energy but no matter can enter or leave the system

Uniform atomic structure- crystal lattice

Orderly arrangement of atoms= repeating patterns that determine shape

primary body waves

P waves cause the ground to compress and expand, that is, to move back and forth, in the direction of travel. They are called primary waves because they are the first type of wave to arrive at seismic recording stations. P waves can travel through solids, liquids, and even gases.

native elements minerals

occur in nature in a pure or nearly pure state; usually metal -gold, carbon, graphite, diamonds, silver, copper, platinum, mercury, sulfur

Porphyritic texture

Porphyritic texture displays a mixture of visible and microscopic crystals. It speaks to a more complex cooling history - multi-stage cooling history

The deductive approach

Postulate a theory Devise a test of that theory Refine the theory based on the results of the test

Taxonomy

Primary level- igneous rock Second level- intrusive ( big crystals) or extrusive (some or all little crystals) Third level - silica content (color and mineral content)

DEPOSITION

Sediments cease moving, and are buried by other sediments.

composition of mantle

Silica, iron, and magnesium.

crust composition

Silicon, oxygen, aluminum, iron, and magnesium.

What controls the atomic arrangement?

Sizes and packing of atoms The way the atom bonds

Sheet silicates

Tetrahedra bond into sheets, which may be weakly connected to one another Micas and clay minerals Cleave in one direction, between the sheets Built from tetrahedra which share all three of their bottom corner oxygens thus forming sheets of tretrahedra with their top corner available for bonding with other atoms

Double chains

Tetrahedra bond to form double chains Amphibole Chains are strong Cleave parallel to double chains, 2 non perpendicular angles

Frameworks

Tetrahedra bonded together with other elements in a in 3d framework All 4 oxygens are bonded Strong bonds, tend to fracture but not cleave Quartz and feldspar

what is plate movement caused by?

friction drag created between the plates and differences in plate densities

what are the two types of rifts

narrow rifts- characterized by a high density of highly active divergent boundaries broad rifts- have numerous fault lines but they are distributed over wide areas of deformation

can Science prove anything to be absolutely true?

no

how does geology apply to non-geologists?

non geologist interact with geologist when they brush their teeth, write with a pencil, climb a mountain, enter a cave, canoe, look out a window, turn on a light, drive a car

when/how does continental collision occur?

when oceanic crust connected by a passive margin to continental crust completely subjects beneath a continent an ocean basin closes and continental collision begins

when does transpression occur?

when there is a component of compression in addition to the shearing motion. these forces build up around the area of the bend, and create mountains in the restraining bend around the fault.

plate boundary

where two plates meet and move relative to each other. This is where we see plate tectonics in action - mountain building, triggering earthquakes, and generating volcanic activity

rock three level taxonomy

- All rocks are classified in a three level taxonomy. The first is whether it's igneous, sedimentary, or metamorphic - Igneous rocks are subclassified into intrusive or extrusive - Intrusive rocks always have a phaneritic texture, meaning all mineral crystals are visible - Extrusive rocks have a variety of textures

Transform boundaries

- Also called strike-slip - the plate slide horizontally past each other - Because no hot material rises (like divergent plate boundaries) and no material sinks into the hot interior of the earth, there are few volcanoes

Mesosphere:

- Also known as the lower mantle. - More rigid and immobile than the asthenosphere - It is extremely high temperatures and pressure

The third level of classification is based on composition

- Because all igneous rocks are dominantly composed of silicate minerals, they are classified on the basis of the amount of silica they contain - Dark color= low silica - mafic - Light color=high silica - felsic

Convergent boundary with collision

- Collision of two continental plates - Often there is not volcanic activity associated with this type of plate boundary - Diffuse zone of earthquakes mostly shallow but sometimes intermediate in depth - Convergent continental collision boundary often site of mountain building - All high topography is the result of this collusion between india and eurasian plates - Convergent boundaries with collusion of two continental plates; no seafloor age

Outer core

- Entirely liquid - It's liquid nature and it's rotations produce the Earth's magnetic field, which is vital to the sustaining of life on Earth.

Stages of divergence

- Form a continental rift - Form a narrow ocean basin - Form a mature ocean basin

Convergent boundary with subduction

- Lines of volcanoes roughly parallel to plate boundary, general forms tight lines - Volcanoes are located on overriding plate - 2 oceanic plates; more accurate shape loans of volcanoes form volcanic arc -arc is usually convex in the direction of the downing plate - Shallow earthquakes occurring on both sides of the plate boundary - Deep and intermediate occurring on one side of the boundary - Deeper quakes are on overriding plate side and tend to form bands at increasing depth and at increasing distance from the plate boundary - Plate boundary corresponds exactly to DEEP TRENCH (topography) - Overriding plate shows shallow water or island in an arcuate (curved like bowl) shape [topography] - Convergent boundaries have no consistent seafloor age (seafloor age)

How are igneous rocks formed?

- Magma rises because it is buoyant- liquid magma is less dense than the surrounding rock so it rises -If the magma is buoyant enough it will rise to the surface and trigger a volcanic eruption but often its rise stalls beneath the surface where it forms a magma chamber - Wherever the magma end up it begins to cool and crystallize, forming the interlocking mineral texture characteristic of igneous rocks

Divergent boundary

- Only sporadically associated with volcanoes - Boundaries show up very clearly in earthquake data - Earthquakes are Shallow and confined to a 10 km wide region around the boundary - Width of the age bands can indicate how fast the ridge is spreading - Topography follow the peak of a seafloor mountain ridge - Water depth is greater on each side of the plate boundary - Ridge crest at average depth of 2500m - Transform fault or fracture zones perpendicular to the spreading center, "Scar" of the offset in the ridge when that part of the oceanic crust was formed

Earthquakes at trenches

- Quakes are especially abundant and large near the oceanic trenches - The subduction was the explanation for the deep earthquakes near trenches - Earthquakes at ocean trenches are both shallow and deep, with deeper ones situated progressively farther inland from the trenches

Inner core

- Solid - Immense pressure causes this layer to be solid. - Highest density layer

lithosphere

- Solid top layer of Earth. - Strong. - Oceanic lithosphere is thin and rigid. - Continental lithosphere is thicker and more plastic than the oceanic lithosphere.

two differences between the oceanic crust and the continental crust.

- The continental crust is much thicker than the oceanic crust. Continental crust is about 50 km or 30 miles thick while the oceanic crust is only 10 km or 6 miles thick. - The oceanic crust makes up most of the ocean floor while continental crust makes up most of the land floor

Asthenosphere:

- The layer below the Lithosphere - Weak - It is mechanically weak, and the most liquid part of the mantle; thus, this layer moves and flows but is not entirely liquid.

Subduction can also happen where oceanic lithosphere converges with oceanic lithosphere

- The younger plate is warmer and thus less dense - The denser, older plate subducts

what happens when a plate diverges?

- When the plates diverges, the crust is thinned and hot asthenosphere rises to fill the gap, this triggers decompression melting, because melting rock depends on pressure as well as temperature - Peridotite from the mantle is partially melted, creating basalt magma

what do geologist study?

- interpret rocks and fossils to unravel earth's history - look at the distribution and evolution of organism's on the planet and how that's changed - identify potential risks from natural hazards - figure out where to find groundwater supplies to support agriculture in regions of low precipitation - find and manage vital energy recourses - apply what we've learned on earth to our neighbors in space

The speed of cooling depends on where it cools and the size of the mineral crystals depends of the speed of cooling

- surface/fast cooling= tiny crystals - Deep in earth/slow cooling= large crystals - Phaneritic-intrusive, large crystals, easily visible to the naked eye, coarse grained, plutonic - Aphanitic- fine grained, extrusive/volcanic

mohorovicic discontinuity

- the base of the crust is characterized by a large increase in seismic velocity, which measures how fast earthquake waves travel through solid matter - the change in wave direction and speed is caused by dramatic chemical differences of the crust and mantle

evidence that supports plate tectonics

- the mid atlantic ridge with rock chemistry and dimensions unlike the mountains found on the continents - seafloor spreading - varying rates of movement between the newly formed plates - mid ocean ridges were younger than the surrounding ocean floor - the alignment of magnetic north in many rocks was nowhere close to the earth's current magnetic north - wadati-benioff zones

Convection

- the transfer of heat via the movement of hot material - The mantle is solid, but below the lithosphere it is hot enough that it flows very slowly, with the hottest material moving up or convecting - Mantle convection drives plate motion - The lithospheric plates move in response to mantle convection. Triggering volcanoes and earthquakes along their edges as they move

Box models

-A mathematical way to understand how systems function -Each box in the model is a place where matter being studied is stored -Arrows drawn between boxes depict the movement of matter from one reservoir to another and the process that moves that matter from one box to another

system

-A system is a group of interacting parts that form a complex whole -Earth is a system -Systems consist of matter

Exceptions to uniformitarianism

-Not every processes that has affected earth is occurring in the present -For those processes that do, their rates and frequencies are not constant

ionic bond

-The electrical attraction between oppositely charged ions forms an ionic bond (or electron transfer bonds) - 90% of all minerals are ionically bonded - forms between a metal and non metal

earth's energy source

-The sun is the ultimate energy source for cycles that occur at depth in the earth -Earth's internal heat is also an energy source for certain processes

Sedimentary rocks

-are formed from rock debris (sediment) -They are composed of rounded sediments grains cemented together -Sediment is either eroded from other rocks or created by chemical processes -The sediment is deposited in horizontal sheets, causing sedimentary rocks to be layered

Tidal rhythmite

-each layer of sentiment was deposited by a separate daily tide -Thin layers were deposited by small (neap) tides, thick layers by high (spring) tides -A year consisted of more days billions of years ago -The earth used to rotate faster than it does today -The moons gravitational tug has slowed earth rotation over time

Uniformitarianism

-processes we observe today were active in earth's past -The present is the key to the past -The effects of todays process are similar to the effect of those same processes in the past

what is geology?

-the origin, structure, composition, and history of earth - the study of earth's internal structure's, its surface landforms and the processes that formed them

mohs hardness scale

1. Talc 2. Gypsum 3. Calcite 4. Fluorite 5. Apatite 6. Orthoclase 7. Quartz 8. Topaz 9. Corundum 10. Diamond

Ultramafic

45% silica

Mafic

45-53% silica

Intermediate

53%-75 % silica

Elements

A chemically distinct substance whose smallest unit is an atom

A rock is

A solid aggregate of minerals

What is a theory?

A theory is something that scientists are strongly confident is correct. It is the pinnacle of scientific believability

In what geological era do we live in?

Cenozoic

Modern atomic theory

All matter is composed of atoms Atoms in one element differ in properties from atoms of another element A compound consists of two or more elements. Elements combine in whole number ratios

when is an atom most stable

An atom is most stable when it has a full outer shell Octet rule - outer shell holds 8 electrons to be full First shell has 2, the 2nd 8, and the 3rd 8

Another factor in melting rock is the water content

At subduction zones, the downgoing slab of oceanic crust introduces water into the mantle, melting it. As the magma rises it cools and crystals form

how are compounds created

Atoms bond together chemically to form compounds

Why do mineral properties vary?

Bonding and packing of elements crystal shape/lattice Chemical composition Type of bonds

WEATHERING

Breakdown of rocks at the Earth's surface into smaller fragments of the same composition and/or chemically altered into different minerals, or elements and molecules (all called sediments).

Non Silicates

Carbonate group minerals compose an important class of sedimentary rocks The crystal structure of these minerals does not contain silica-oxygen tetrahedra Made up of carbonates, oxides, halides, sulfides, sulfates, and phosphates Oxide and sulfide minerals are the major ores for precious and industrial metals - cement Sulfates include gypsum which is used in wallboard Halides provide us with table salt and other important salts Phosphates ultimately provide all the world's phosphorus an essential nutrient for life

Polymorph

Chemical compound that can crystallize into more than one form/structure

Ways of knowing

Common sense Direct observation (unaided) - empirical knowledge Direct observation (aided) - empirical knowledge Authority of others Authority of texts

Two types of crust on the seafloor

Continental crust Oceanic crust

composition of continental crust

Continental crust is made of low density igneous and sedimentary rock.

collision zones

Continental crust is too buoyant to subduct so where two continental plates converge, neither one dives. Instead, they are stacked on top of each other, forming a large, non volcanic mountain range

For most of geological history, it was believed that

Contractionism- an expanding and contracting earth Permanentism- the continents and oceans have always been generally where they are Geosyncline theory- thick sedimentary deposits formed from eroding rock which somehow develop into fold belt mountains Lang bridges - fossil record ( same type of fossils on several continents)

controlled experiments

Controlled experiments are important in geology but not all geological processes can be tested by an controlled experiment

what causes different shapes in minerals and different minerals?

Different atomic arrangements

Plate tectonics

Earth's surface is broken into several plates Those plates all move, rubbing against one another which cause earthquakes, volcanoes and growth of mountain ranges along plate boundaries

Two reasons for the scientific community's rejection of continental drift

Failure of imagination- we tend to support the status quo or to believe ourselves Extraordinary claims require extraordinary supporting evidence Occam's razor states: Scientists wanted to know how the continents moved through the solid rock of the seafloor

Metamorphic rocks

Formed when high heat and or pressure transforms one rock into another without melting it. They are composed of interlocking crystals that are often aligned with each other

Glassy texture

Glassy texture is when no minerals are able to form

areas of the study of earth

Hydrosphere Atmosphere Geosphere Biosphere Cryosphere

METAMORPHISM

Increased heat and/or pressure, associated with DEEP BURIAL and/or contact with hot magma. Rock is NOT melted, but elements and molecules can recombine to form new minerals while the rock remains in a solid state.

composition of the core

Iron and nickel.

Sources of knowledge

Logical: reason/logic/common sense Empirical- direct observation -Unaided -Using aids Intuitive: inspiration/revelation/faith Authoritative: information received from people/books

ERUPTION

Magma erupts into the atmosphere or water at Earth's surface, transforming into solid (igneous) rock. Elements and molecules in the magma combine into distinct mineral crystals.

where is magma formed?

Magma is formed deep in the earth, where the temperature is much higher than it is at the surface

what causes darker colors?

Magnesium and iron cause darker color- the more of those elements it contains the less silica there is High silica minerals are light in colors Low silica minerals are darker in color Dark and light - mafic and felsic

Silicates

Most abundant and most important mineral group. they are build around a molecular ion called the silicon-oxygen tetrahedron

Minerals are

Naturally occurring Inorganic solid Crystalline (ordered internal molecular structure) Definite chemical composition Minerals are compounds that have an organized crystalline structure

Inductive approach

Observe a phenomenon Hypothesis Experiment Revise hypothesis based on the results of the experiment Reviewed by others Scientific theory

which is more buoyant, oceanic crust or continental crust?

Oceanic crust is dense as it's made of basalt. Oceanic crust is less buoyant than continental crust. - Where a lithospheric plate consisting of oceanic crust converges with a lithospheric plate consisting of continental crust the oceanic plate dives deep into the earth where it melts. The magma this generates is buoyant, so it rises to the surface and erupts in volcanoes

composition of oceanic crust

Oceanic crust is made of high density igneous basalt rocks.

the geologic eons from youngest to oldest.

Phanerozoic, Proterozoic, Archeon, and Hadeon.

Pyroclastic, or fragmental, texture

Pyroclastic, or fragmental, texture reveals that the rock was formed during an explosive eruption

Single chains

Pyroxene Tetrahedra bond together to form single chains Chains are strong Cleave parallel to chains, 2 perpendicular angles

BURIAL (deep)

Rocks are buried by the deposition of younger, overlying rocks, or by plate tectonic processes. Associated with METAMORPHISM.

BURIAL (shallow)

Rocks are buried by the deposition of younger, overlying rocks. Associated with COMPACTION and CEMENTATION.

secondary body waves

S waves shake the ground in a shearing, or crosswise, motion that is perpendicular to the direction of travel. These are the shake waves that move the ground up and down or from side to side. S waves are called secondary waves because they always arrive after P waves at seismic recording stations. Unlike P waves, S waves can travel only through solid materials.

How can something be accepted as true

Science accepts something as true only if it can be directly observed as true

Evidence/data of tectonic plate theory

Seafloor bathymetry (topography) - seafloor mapping Multi beam sonar (modern techniques) - can detect water column phenomena like bubbles or gas seeps Seafloor composition and age -Dredging Underwater mountain ranges had morphology, dimensions, and rock chemistry that were not found on continents Volcanic passive margins

seafloor magnetic stripes

Seafloor magnetic stripes are symmetric on either side of the mid ocean ridges Scientist could match the pattern of reversals recorded in a rock sequence like a barcode to obtain the distribution of seafloor rock ages

EXHUMATION

Solid rocks (formerly buried deep under the Earth's surface) are brought to the surface by the removal of overlying rocks.

what type of rock is found at subduction zones

Subduction zones are dominated by igneous rocks of intermediate composition

silica tetrahedron

The basic building block of all silicate minerals Tetrahedra combine in different patterns in different silicate minerals seen in cleavage patterns Minerals with low silica content share few oxygens and have simple structures (independent, chains) - olivine, pyroxene

continental drift theory evidence

The continents fit together like puzzle pieces - used continental shelves (underwater) as true edges of the continents which produced a better fit for continents to fit together Matched geological patterns across oceans This led him to propose that all the continents were joined together to form a global supercontinent called pangaea

COMPACTION

The deposition of rock layers above puts pressure on deeper sediments, causing the grains to be pushed closer and closer together, and reducing pore space between sedimentary grains.

Bowen reaction series

The more silicon a mineral had in it the lower its melting temperature. So as partial melting of mantle peridotite occurs, it's the most silica rich minerals that melt first, creating a basalt magma

what is the oceanic crust composes of?

The oceanic crust is composed of igneous rock, basalt

Cementation

The process by which sediment is cemented or glued together via mineralization.

Crystallization

The process of liquid rock (lava or magma) cooling or freezing into solid rock. Magma and lava (liquid rock) have many components, thus crystallization is a complex process as different components cool at different temperatures.

Erosion:

The process of sediment that has been weathered being moved or transported.

Melting

The process where rock is transformed into magma through extremely high temperatures that are only found deep below the earth's surface.

what happens to the seafloor the farther it gets from the mid ocean judge?

The seafloor gets older the farther it is from the mid ocean ridge

Subduction

This process occurs when an oceanic plate descends under a tectonic plate that is less dense than the oceanic plate; this causes the oceanic plate to be removed from the surface, and causes the biggest earthquakes possible due to the fact that the oceanic plate can become locked during its descent.

Covalent bonds

Two atoms share electrons in their outer shell to complete their valence shells; occur between non metals

what pattern is revealed when earthquakes are plotted?

When Scientists plotted the position of earthquakes the maps revealed that they occur in bands

ion

When an atom gains or loses an electron to fill its outer shell it becomes an ion Cation - positive charge Anion- negative charge

Do igneous rocks of subduction zones have a different composition?

Yes!

where do mid ocean ridges occur?

a continental plate as a rift zone that expands to the point of splitting the plate apart with seawater filling in the gap

electronegativity

ability to attract electrons

hotspots

an area of the lithosphere plate where molten magma breaks through and creates a volcanic center, islands on the ocean and mountains on the land. the only types of volcanism not associated with subduction or rifting zones at plate boundaries

Hot spots

are plumes of hot material that rise from very deep in the earth; much deeper than the bottom of the lithosphere. As plates move over these plumes, a chain of volcanoes is erupted

how does new ocean or oceanic lithosphere form?

as rifting and volcanic activity progresses, the continental lithosphere becomes more mafic and thinner with the evantual result transforming the plate under the rifting area into oceanic lithosphere

Where are earthquakes shallow?

at ocean ridges

when do tectonic plates not move

at passive margins

where do the largest earthquakes and tsunamis occur?

at subduction zones

Where is oceanic crust destroyed?

at trenches

rock forming minerals

common minerals

Alfred wegener

continental drift theory; which suggested that the earth's continent drifted across the globe moving like ships through the ocean

divergent boundaries - continental rift zones

continental rift zones occur at weak spots in the continental lithospheric plate

Are covalent or ionic bonds stronger?

covalent

Wadati-Benioff zones

deep earthquake zones that congregate in planes that started near the surface around ocean tranches and angled beneath continents and island arcs

luster

describes how the mineral looks (is it shiny, dull, silky, pearly, glassy?)

what are minerals made of

elements

streak

examines the color of a powdered mineral and can be seen when a mineral sample is scratched or scraped on an unglazed porcelain streak plate

Felsic

greater than 75% silica

crystal habit

how their crystals grow and appear in rocks; crystal shapes are determined by the arrangements of atoms within a crystal structure anhedral- when minerals are constrained so they do not develop their typical crystal habit subhedral- partially formed shapes euhedral- crystal with a perfectly formed unconstrained shape

where are magnetic flip flops recorded?

in rocks

Igneous rock

interlocking mineral crystals that grow as magma cools and solidifies/ formed from melted rock material called magma

8 elements make up most of the rocks in the earth's crust and several are part of the earth's core and mantle

iron, sodium, calcium, oxygen, magnesium, silicon, aluminum, potassium

hardness

measures the ability of a mineral to scratch other substances

cleavage and fracture

minerals often show characteristic patterns of breaking along specific cleavage planes or show characteristic fracture patterns. Cleavage is given in terms of the quality (perfect, imperfect, none), the # of cleavage surfaces, and the angles between surfaces

where are the transform boundaries found?

on the ocean floor around the mid ocean ridges

Quartz

one of the most common covalently bonded mineral (sio2)

how is magma generated in hotspots?

originate from the superheated material from as deep as the core that reaches the earth's crust as mantle plume outsourced from the mantle

Epistemology

philosophical branch the explores how we know what we know

active margins

places where oceanic and continental lithosphere tectonic plates meet and move relative to each other

convergent boundaries

places where plates move toward each other

divergent boundary

plates move apart

transform boundaries

plates slide past each other

special properties

specific gravity- the weight of a mineral specimen relative to the weight of an equal volume of water some iron-oxide minerals are magnetic some minerals and mineraloids scatter light-iridescence striations on mineral cleavage faces are optical property that can be used to separate plagioclase Feldspar from potassium feldspar some are florescent and give off visible light when exposed to ultraviolet radiation some are glow in the dark

how are hotspots initiated?

starting in divergent boundaries during supercontinent rifting

how is subduction initiated?

subduction zones start as passive margins and then gravity initiates subduction and converts the passive margin into an active one

why does subduction not occur in some places?

the bond holding the oceanic and continental plates together is stringer than the downwards force created by the different plate densities

the Wilson cycle

the cycle of ongoing origin and breakup of supercontinents

Scientific method

the general way that scientific knowledge is gather and evaluated

what does sinistral movement mean?

the opposing plate moving to the left

what does dextral movement mean?

the opposing plate moving to the right

divergent plate boundaries

the plates pull apart, thinning the lithosphere and causing volcanic eruptions of basalt. This creates oceanic crust, moving the continents apart

the rock cycle

the system by which one rock type is transformed into another rock type through geological processes

how do these rifts create magma?

through decompression melting

bond type

varies with chemical composition

in seafloor spreading

volcanic eruptions at mid ocean ridges create new oceanic crust, moving the continents apart

when does subduction occur?

when a dense oceanic plate meets a more buoyant plate, like a continental plate or warmer/younger oceanic plate

collision

when continental plates converge and subduction does not occur