Geology Exam I (Prelude, Ch. 1-3, Interlude A)

Different ways minerals can form (5)

- solidification - precipitation - solid-state diffusion - biomineralization - precipitation directly from a gas

Evidence for Continental Drift

1) "puzzle like fit" 2) location of past glaciations 3) distribution of climatic belts 4) distribution of fossils 5) matching geologic units

Rock Basics

1) Coherent Forming a whole - loose pile of sediment is not a rock! 2) Naturally occurring solid Concrete and bricks are not rocks! 3) An aggregate of minerals or a body of glass A collection of many mineral grains/crystals attached to one another Glass = ex) obsidian

Seven mineral classes

1) Native elements 2) Oxides 3) Halides 4) Carbonates 5) Sulfates 6) Silicates 7) Sulfides

Geologists address two kinds of questions: ________ & _________

1) fundamental (formation & composition of planets) 2) practical (how to find oil & minerals)

Rock physical characteristics

1) grain size and shape 2) composition 3) texture 4) layering

Steps of the Scientific Method

1) observation 2) ask a question 3) form hypothesis 4) make prediction based on hypothesis 5) test prediction 6) use results to make new hypothesis/predictions

Atmosphere is divided into four layers:

1) troposphere 2) stratosphere 3) mesosphere 4) thermosphere All weather occurs in the troposphere.

Continent-Continent Convergent Boundaries

Aka Continental Collision No volcanoes Deep Earthquakes Rocks of any type may convert into metamorphic rocks from increased temperatures and pressures.

Biosphere

All living organisms, as well as the portion of the Earth in which living organisms exist, is known as the biosphere. Life needs liquid water Biosphere overlaps with geosphere, hydrosphere and atmosphere.

Puzzle-like fit of the continents

Almost as soon as maps of the Atlantic coastlines became available in the 1500s, scholars noticed the fit of the continents

Ocean-Continent Convergent Boundaries

Denser oceanic plate is subducted beneath the continental plate Ocean trenches mark the boundaries Compression of continental plate creates mountain chains These mountain chains may become volcanic if magma rises to the crust

Matching geologic units

Distinctive belts of rock occur on both South America and Africa. These belts match up when the present-day Atlantic Ocean is removed. Likewise, Paleozoic mountain belts on either side of the Atlantic Ocean match up.

Layers of Earth's Interior

Five parts: 1) crust 2) moho 3) mantle 4) outer core 5) inner core

Location of past glaciations

Glaciers are sheets of ice that flow across the land. Till and striation serve as evidence that the region was covered by a glacier. Glaciers form at high latitudes (polar) Wegner found glacier deposits in South America, Africa, southern India, Antarctica, and Australia.

grain size and shape

Grain size Microscopic 🡪 size of a car Grain shape Equant = same dimensions in all directions Inequant - dimensions not the same

what holds rock together?

Grains in rock stick together to form a coherent mass 1) because they are bonded by natural cement mineral material that precipitates from water and fills the space between grains 2) they interlock with one another like pieces of a jigsaw

Seafloor spreading

Harry Hess compiled the evidence that new sea floor is created at mid-ocean ridges, moves away from the ridges, and then subducts back into the mantle. Seafloor spreading hypothesis provided explanation of how continental drift occurs.

Generally Inorganic

It does not come from living things Not matter that makes up plant and animal bodies Ex) Table Salt (Halite) NOT Sugar

Naturally Occuring

It is found in nature Ex) Diamonds found in a diamond mine NOT - synthetic diamonds created in a lab

Crystalline Solid

Minerals are in a solid state Not liquid or gas Ex - Ice formed Naturally is considered a mineral NOT - liquid water, ice in your freezer

Solar System

Our Sun's gravitational pull holds on to many objects that, together with the Sun, comprise the Solar System - 99.8% of the mass of the Solar System is the Sun

lithosphere

Outer 100 - 150 km of Earth Behaves relatively rigid Upper crust and cool uppermost mantle The plates of plate tectonics

Geocentric

Ptolemy's model - Earth is center of universe

The velocity of plate motion can be described in two ways.....

Relative plate velocity describes motion of one plate relative to another. Absolute plate velocity describes motion compared to a fixed reference point beneath the plate.

clastic versus crystalline rocks

Rocks whose grains are stuck together by cement are called clastic rocks Rocks whose crystals interlock with one another are called crystalline rocks

What is the difference between the lithosphere and the asthenosphere? At what depth does the lithosphere-asthenosphere boundary occur? Is this above or below the Moho? Is the asthenosphere entirely liquid?

The lithosphere is everything above the part of the mantle which can flow and the asthenosphere is everything including and below. the lithosphere-asthenosphere boundary occurs at 1280 C approximately at 150 km. It is below the moho. Not entirely liquid, as it behaves more like plastic which allows rock to flow.

definite chemical composition

Unique chemical make-up Fixed ratios Ex) Halite - NaCl

Distribution of Climatic Belts

Wegener found a distribution of coal, reef, sand-dune and salt deposits on Pangea. Exposures align in continuous bands that occupy appropriate latitudes.

Continental drift hypothesis

Wegener proposed that Pangea broke apart, and the landmasses moved away from each other to form the continents we see today

Alfred Wegener

a German meteorologist who hypothesized that the continents used to fit together as a single supercontinent, which he named Pangaea.

Mantle

a layer that ranges in thickness from 2,820 to 2,890 km. It lies between the crust and the core Upper Mantle = down to depth of 660 km Lower Mantle = 660-2,890 km

Hot Spots

a location at the base of the lithosphere, at the top of a mantle plume, where temperatures can cause melting - NOT asscoiated with plate boundaries

Atmosphere

a mixture of gas (air) that surrounds the planet - Mostly nitrogen and oxygen!!!

hypothesis

a possible explanation that can explain a set of observations

luster

a property that refers to the way that a mineral surface scatters light. The two main subdivisions of luster are metallic and nonmetallic

How old is the Earth?

about 4.6 billion years old

Hawaiian Islands (hot spot formation)

an example of a hot-spot track. Plates will move over The islands increase in age with distance from the present hot spot. Only the volcano under the hotspot is active

Solidification (freezing)

when a liquid cools and turns into a solid - solidification of molten rock

Scientific Law

concise statements that completely describe a specific relationship or phenomenon Ex) Newton's law of gravity

what thickness of crust do regions with mountains have

continental crust = 30 to 50 km mountain = thickest portion

color

diagnostic of some minerals (malachite) but a poor indicator for others (quartz). Least reliable property when identifying minerals

Igneous rocks

form by the solidification of molten rock

sedimentary rocks

form either by the cementing of fragments or by the precipitation of mineral crystals

fracture/cleavage

fracture - the tendency of a crystal to break along irregular surfaces --> Conchoidal, uneven, splintery, Hacky cleavage - the tendency for a mineral to break along lattice planes with weaker atomic bonds. --> one direction, two direction at 90 degrees, two directions not at 90 degrees

precipitation

from a water solution takes place when dissolved ions bond together to form crystals that settle out of the water Ex) Salt crystals

Minerals must.... (5)

have a specialized geologic definition. 1) Naturally Occurring 2) usually inorganic 3) crystalline solid 4) with a definite chemical composition. 5) Is homogeneous - Cannot be divided mechanically into smaller components

Why is glass not a mineral?

it does not have a fixed crystalline structure

Silicates

make up over 95% of the Earth's crust Composed of oxygen and silicon - Two most abundant elements in crust!!!!!! Creates silicate ion (SiO44-) Central silicon atom and four surrounding oxygen atoms

what causes hot material to move to the surface and cool material to sink in the convection currents of plate tectonics?

more dense (cool) material sinks, less dense (hot) material rises

precipitation directly from a gas

occur around volcanic vents or around geysers Ex) Yellow sulfur deposits

Mineralogist

people who specialize in the study of minerals - About 4,000 minerals exist

metamorphic rocks

pre-existing rocks change in response to change in temperature, pressure, or chemical environment

Paleomagnetism

record of the Earth's magnetic field in the past Provided proof of both continental drift and seafloor spreading

rock composition

refers to the chemical makeup of a rock, as represented by the proportions of different minerals

Moho

region that defines the boundary between the Earth's crust and mantle

Hydrosphere

represents the water on Earth (LIQUID) - Oceans, surface water, and groundwater

solid-state diffusion

results from the movement of atoms or ions through a solid to arrange into a new crystal Ex) Garnets

Geologist

scientist who studies the Earth

hardness

scratching resistance of a mineral, which is directly linked to atomic bond strength hardest mineral: diamond softest mineral: talc

small versus large crystals

small: Most common, lack of space, fast crystallization large: Less common, adequate space without interference of other crystals, slow and steady crystallization

Geology

study of the Earth's systems. It is a synthesis of many sciences - geology applies basic concepts of physics and chemistry.

Biomineralization

takes place when minerals grow at the interface between the physical and biological components of the Earth System Ex) shells grow on organisms and are made of minerals

Andes Mountains - Western South America

tectonic boundary type: convergent plates interacting: continental/ocean

Japanese Islands and Trench

tectonic boundary type: convergent plates interacting: ocean/ocean

East African Rift

tectonic boundary type: divergent plates interacting: continental/continental

Mid Atlantic Ridge

tectonic boundary type: divergent plates interacting: ocean/ocean

Himalaya Mountains

tectonic boundary types: convergent plates interacting: continental/continental

streak

the color of a mineral crushed on a porcelain paint Every mineral will have the same streak, even if they are different colors (quartz) Minerals must have a hardness <6

Cryosphere

the frozen portion of the hydrosphere - Includes ice, glaciers, permafrost Cryo comes from Greek word kyro, meaning very cold or ice-like

Motto of principle of uniformitarianism

the present is the key to the past

Cosmology

the study of the overall structure and history of the Universe

What is the primary factor of some regions having high elevations than others?

thickness of the underlying core

The surface of Earth is not smooth. The variation in land surface is known as:

topography

Crust

two kinds of crust: 1) Continental crust is thicker and less dense 2) Oceanic crust is thinner and more dense

Divergent boundary

two plates move away from each other - crust is formed ex) Mid Atlantic Ridge

Theory

A generally accepted explanation that has accumulated a substantial body of support through observations and experiments. Ex) Plate tectonics

Transform boundary

A plate boundary where two plates move past each other in opposite directions - crust neither created or destroyed BUT huge potential for earthquakes ex) San Andreas Fault in CA

Convergent boundary

A plate boundary where two plates move toward each other - crust is destroyed ex) mountains

asthenosphere

Below 150 km Behaves relatively plastic and can flow Driving force of plate tectonics

texture

Coarse-grained Crystals or grains large enough to be seen with the eyes Fine-grained Crystals or grains are not large enough to be seen with the eyes

Continental Divergent Boundary

Continental-Continental lithosphere AKA Continental Rifting Continental rift is a linear belt in which continental lithosphere pulls apart As rifting continues, new oceanic lithosphere is formed at the diverting center

Heliocentric

Copernicus model - Sun is center of universe

Distribution of fossils

Mesozoic fossil organisms occur on many of the southern continents, but these creatures could not migrate across an ocean.

Silicate ion commonly bonds to:

Sodium (Na) 🡪 Plagioclase Feldspar Potassium (K) 🡪 Mica, Orthoclase Feldspar Calcium (Ca) 🡪 Amphibole Magnesium (Mg) 🡪 Olivine, Pyroxene Iron (Fe) 🡪 Olivine, Pyroxene

layering

Some rock bodies appear to contain distinct layering The layering in sedimentary rocks is called bedding The layering in metamorphic rocks is called foliation

Oceanic-Oceanic Convergent Boundary

Subduction: one plate sliding beneath another One oceanic plate begins to subduct beneath another oceanic plate Can create island arc from erupting magma

Big Bang Theory

The Big Bang Theory proposes that all matter and energy in the Universe started out as a single infinitesimally small point. It exploded and has been expanding ever since. The Universe began 13.8 billion years ago

Plate Boundaries

The breaks between plates are known as plate boundaries - distribution of earthquakes defines the position of plate boundaries!!

Core

The central part of Earth Outer Core - 2,890 - 5,155 km depth Liquid iron and nickel Liquid iron convection flow generates the Earth's magnetic field Inner Core - 5,155 - 6,371 km depth Solid iron and nickel due to increased pressure

Geosphere

The solid Earth, from the surface to the center Consists of: Organic chemicals Minerals Glass Melts Rocks Grains Sediment Metals Volatiles

polymorphs

Two different minerals that have the same composition, but different crystal structures ex) diamond & graphite

Oceanic Divergent Boundary

Two oceanic plates move apart by seafloor spreading An open space does not develop, but new oceanic lithosphere forms continually Process takes place at mid-ocean ridges Symmetric shape