Geo 102-Exam 1

Geology 102 with Sheilds at Illinois State University

About this deck

By: Katy Winge
Textbook:

Essentials of Geology with Geotours Workbook (Third Edition)
Created: 2012-02-05
Size: 72 flashcards
Views: 153

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Define Geology

Geology is the science that studies: Earth materials, earth's history, and earth's processes

Parts of an atom

proton, neutron, electron

Ion

atoms with excess positive or negative charge (gain or loss of electrons from outermost shell).

Ions dissolved in water will combine to form what?

compounds

Cation

positive charge, lose electrons

Anion

negative charge, gain electrons

Isotope

elements with different numbers of neutrons in the nucleus

What are the types of bonds?

Van der Waals, Ionic, Covalent, Metallic

Van der Waals

weakest bond-weak attraction, softest minerals

ex: graphite

Ionic

transfer of electrons between cations and anions-moderate strength, moderate hardness

ex: sodium chloride (salt), NaCl

Covalent

strongest bond-electrons are shared between atoms, hard mineral

ex: oxygen (O2)

Metallic

electrons are shared but move about freely between ions making metallic minerals good conductors of electricity

ex: copper, gold

How does bond strength relate to mineral hardness?

The stronger the bond, the harder the mineral

What are the most common elements on Earth by weight?

Oxygen and Silicon

What are the requirements a substance must meet to be a mineral?

Naturally formed, solid, formed by inorganic processes, specific chemical composition, characteristic crystal structure

Properties of Minerals

Crystal form, habit and cleavage, hardness, luster, color, streak, and density

Crystal form

isometric (cubic), tetragonal, hexagonal, monoclinic, etc. The internal arrangement of atoms or ions in a mineral

Cleavage

in one direction (muscovite), in two directions (feldspar), in three directions (halite)

Hardness

Mohs Hardness Scale fingernail, copper penny, glass, streak plate 1-weakest, 10-hardest. 1 talc 10 diamond 7 quartz

Luster

metallic (metal like) vs. non metallic (vitreous-glassy, resinous-resin, pearly-pearl, greasy-slippery)

Color

color of mineral, color of streak

Density

we compared the weight of quartz to all others

Rock

a coherent, naturally occurring solid, consisting of an aggregate of one of more minerals, or a mass of natural gas or organic matter

Plutonic

an igneous rock that cools underground

Volcanic

an igneous rock that cools above ground

Aphanitic

fine grained, rapid cooling, small crystals, volcanic (lava), extrusive

ex: rhyolite, andesite, basalt

Phaneritic

course grained, slow cooling, large crystals, plutonic (magma), intrusive

ex: granite, diorite, gabbro

Freeze

to go from a liquid to a solid (most often by abstracting heat)

Magma

molten material below the earth's surface, rises due to density differences and pressure

Lava

molten material above the earth's surface

Intrusive

(plutonic igneous rock) cools and solidifies below the earth's surface --> phaneritic

Extrusive

(volcanic igneous rock) cools and solidifies above the earth's surface --> aphanitic

Mafic

low SiO2, iron, magnesium --> dark colored rocks

Felsic/Silicic

high SiO2, aluminum, calcium, sodium --> light colored rocks

Viscosity

resistance to flow, viscosity increases as silica content increases

honey-high viscosity

water-low viscosity

Texture

overall appearance, related to size, shape, and arrangement of minerals. Texture is related to cooling history of an igneous rock, not its chemistry

ex: glassy texture=very rapid cooling

The source of heat that causes rock to melt

Radioactive decay

Factors that control melting

Temperature, pressure (decreasing pressure melts rocks at lower temp), water (if present, melt at lower temp), composition of minerals matter (white melts sooner, black last)

Types of Volcanoes

Non-explosive (shield volcanoes, basalt plateaus) and Explosive (composite cones, mt st. helens)

Non Explosive Volcanoes

low viscosity (flows easily), low silica content (mafic), basaltic magma (lava)

Explosive Volcanoes

high viscosity (resists flow), high silica content (intermediate, felsic), andesitic or granitic magma (lava)

Why are some volcanoes explosive while others are not?

The viscosity of the magma. Sticky and thick magma doesn't let air out easily, when it is released, it is released explosively.

What are the main types of weathering?

Mechanical and Chemical

Mechanical Weathering

makes smaller pieces, frost wedging, salt wedging, biological wedging, unloading, thermal expansion

Frost Wedging

water penetrates into cracks, expands when it freezes. Must have: adequate moisture, cracks in rocks, and freeze/thaw cycles

Salt Wedging

growth of minerals in cracks. Desert environments, water evaporates, ions in solution combine to form minerals

Biological Wedging

plant roots penetrate into cracks causing cracks to widen. Must have: climate hospitable for plants, adequate moisture and temperature

Unloading

removal of pressure of deep burial

Thermal Expansion

repeated daily heating and cooling of rock, heat causes expansion; cooling causes contraction

Chemical Weathering

chemical alteration of minerals, results in new minerals and ions in solution. Water and acid are essential. It changes the minerals of rock. Hydrolysis, ion exchange, dissolution, oxidation

Hydrolysis

any reaction in which water participates

Ion Exchange

H+ replaces other cations, ex: carbon dioxide+rain becomes acid, dissolves minerals and leaves clay carrying away ions and silica

Dissolution

mineral completely dissolves, leaving only ions in solution, certain minerals dissolve in water

Oxidation

reaction in which elements gain or lose electrons (ex: rust)

What are the factors that influence the rate of weathering?

Rock structures (chemical/mineral composition, physical features), topography, climate (warm and wet weathers faster than cold and dry)

Regolith

a loose layer of broken rock and mineral fragments, dissolved ions, everything broken

Soil

subcategory of regolith

Talus

a rock slope, forms from accumulation from rocks that are physically weathered off a mountain

How does water and wind transport material?

Bedload (material transported by saltation bottom of river), saltation (particle move downstream in short jumps-bouncing), suspension (keeps fine particles suspended in air or water for long periods of time), most material carried in suspended load.

Continental Drift

Proposed by Alfred Wegener in 1915. Wegener proposed that the Earth's surface was dynamic and that land masses moved around and interacted. Hypothesized that at some time in the past, all land masses were one super continent-Pangaea

Lines of Evidence for Continental Drift

1. Matching coastlines

2. Matching geology

3. Glacial Striations

4. Fossil Evidence- glossopteris, mesosaurus: links in SA and Africa during Paleozoic and early Mesozoic eras

5. Apparent polar wandering

Pangaea

the super-continent in which all land-masses were assembled at some time in the past

Plate Tectonics

Brings together continental drift and seafloor spreading, explaining many of the landforms we see on earth and the process which formed them. Why mountains exist, how rift valleys form

Continental-Rift Valley

Divergent plate boundary, Rifts form as the Earth begins to open beneath the continental land

Ocean Midoceanic ridge/Spreading sea floor

Divergent plate boundary, at divergent boundariesnew crust is created as two or more plates pull away from each other. Oceans are born and grow wider where plates diverge or pull apart

Oceanic-Continental

when an oceanic plate pushed into and subducts under a continental plate, overriding continental plate is lifted up and a mountain range is created. Deepest part of subducting plate breaks into smaller pieces that eventually generate earthquakes

Oceanic-Oceanic

When two oceanic plates converge one is usually subducted under the other and in the process a deep oceanic trench is formed. Also results in the formation of undersea volcanoes

Continental-Continental

When two continents meet head-on, neither is subducted because the continental rocks are relatively light and, resist downward motion. Instead, the crust buckles and is pushed up sideways or upwards. (How Himalayas were formed)

Rift Valleys

form as the earth begins to open beneath the continental land

Geothermal Gradient

the rate at which temperature increases with depth in the earth

What is the most abundant element in the earth's atomosphere?

Nitrogen

What bond type requires electrons to move freely to hold atoms together?