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97 Cards in this Set
- Front
- Back
What is Geology?
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Geology is the study of Earth.
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Plate Tectonics
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Plate Tectonics theory explains that the outer shell layer of the Earth, lithosphere, is broken into slabs called plates. Plates move slowly and change size over time.
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Plate Boundaries
Divergent |
Plate boundaries stretch and separate. (move away from each other) As plates separate, the gash is filled with molten material rising from the asthenosphere.
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Plate Boundaries
Convergent |
Plates collide head on into each other. One will plunge into the deeper mantle in a process called subduction. The overriding plate experiences volcanic activity. Earthquakes, mountains, volcanoes form from convergent boundaries.
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Plate Boundaries
Transform |
Plates slide past each other without creation or destruction of the lithosphere.
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Properties of Minerals.
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Luster, Specific Gravity, Density, Crystal Faces, Hardness, Cleavage, Color, Streak
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Luster is..
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the property that describes how mineral surfaces reflect light
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Crystal faces are..
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smooth, flat surfaces with regular geometric outlines. Ex: Calcite and Quartz both six sided but with different crystal faces.
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Density is..
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a measure of the mass of a material divided by its volume.
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Specific gravity is..
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is the weight of a material in air divided by the weight of an equivalent volume of water at 4 'C. Specific gravity and density often have the same value.
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Hardness is..
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is the measure of a mineral's resistance to scratching.
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Mohs Hardness Scale is..
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from 1 to 10. Diamond being the 10. Quartz 7. Calcite 3. Fingernail 2.5; Copper Penny 3.5; Wire Nail 4.5; Glass 5.5; porcelain plate 6.5; pocket knife blade 7.
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Cleavage is..
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description of the flat, smooth planes along which some minerals break and the shape of the resulting fragments.
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Color is...
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not always a reliable property for identifying a mineral because of variations.
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Streak is..
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the color of the residue produced by scratching a mineral on a nonglazed porcelain plate. A mineral may vary in color but the streak is always the same.
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A polymorph is..
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minerals with identical chemical composition but with different arrangements of atoms. EX. Calcite and Aragonite.
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A mineral defined..
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a naturally occurring solid, usually inorganic, with a definite, only slightly variable chemical composition and an ordered atomic structure.
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Color is determined by a mineral's...
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chemical composition
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Most physical properties are determined by...
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atomic structure. EX. Graphite and Diamond, both made out of carbon but diamond is hard and graphite is a 2.
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Silicate Minerals are...
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the primary rock forming minerals in the crust.
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Silicates:
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olivine, pyroxene, amphibole, micas, serpentine, feldspar, quartz, garnet
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Nonsilicates:
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calcite/aragonite, dolomite, magnetite, hematite, corundum, halite, gypsum, gold, copper, chalcopyrite, pyrite, sphalerite, galena
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Carbonate minerals:
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calcite, aragonite and dolomite. Typically precipitate from water.
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Descriptive classifications
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group items of similar appearance.
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Genetic classifications
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group features or phenomena by noting similarities in the process that cause or create them.
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Sedimentary rocks are formed by..
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deposition and precipitation of products formed by the breakdown of older rocks under the ordinary conditions found in Earth's surface environment.
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Physical weathering
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causes rocks to disintegrate into smaller rocks or into even smaller mineral grains.
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Chemical weathering
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involves reactions between minerals and water to produce dissolved ions and new minerals.
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Clastic sediment
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minerals or rock fragments produced by weathering
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chemical sedimentary rocks
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mineral constituents dissolved in water by chemical weathering may later precipitate as new mineral crystals if conditions of water temp, pressure, or element composition change appropriately.
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chemical sedimentary rocks are composed mostly of..
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carbonates, sulfates, common salts, and some oxides. EX: calcite, dolomite, gypsum halite, and hematite
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lithification
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compaction under the weight of accumulating sediment and precipitation of cementing minerals between grains convert loose sediment into consolidated sedimentary rocks.
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bedding
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sedimentary rock's distinctive layering
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Igneous rocks
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crystallize from molten material called magma which originates from melting rock within the Earth. Composed mostly of silicate minerals.
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volcanic rocks
extrusive |
solidify at the surface
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plutonic rocks
intrusive |
solidify beneath the surface
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massive
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rocks that lack layering
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metamorphic rocks
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result from changes of preexisting rocks, occurs at high temperatures, high pressures, conditions found within Earth
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regional metamorphic rocks
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rocks originating at or near the surface are forced down to great depth and have high pressure exerted on them
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contact metamorphic rocks
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seen at bottom of lava flows, most impressive adjacent to igneous intrusions. Magmatic heat together with naturally elevated temperature at depth and large volumes of hot water cause dramatic metamorphic change.
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Hydrothermal metamorphic rocks
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form where hot-fluid reactions with rock are the primary cause of metamorphism. Commonly host important metal-ore deposits.
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Neptunist View
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Abraham Werner (1749-1817) Earth started out as a vast blob of material dispersed in water. Primitive Rocks - plutonic igneous rocks and most metamorphic rocks. Stratified Formations- sedimentary rocks and volcanic rocks
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Vulcanist View
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James Hutton (1726-1797). Inherently hot planet with rocks forming from the fusing of particles by heat, or from solidification of magma rising from the interior. Primitive rocks did not necessarily come first.
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Difference between lava and magma
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lava is molten material ejected from a volcano; magma is molten material below Earth's surface
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pyroclastic materials
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lava fountain blobs, ash, pumice
What shoots out of the volcano when it erupts. |
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Framework for naming igneous rocks:
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composition (minerals present) and texture (size of mineral grains)
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How to categorize magma and igneous rocks:
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Felsic, Intermediate, Mafic, Ultramafic
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Mafic and Ultramafic mostly contain..
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magnesium rich and iron rich silicate minerals, olivine and pyroxene. Produce dark gray to black rocks.
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Intermediate rocks...
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contain hornblende, biotite, or pyroxene and plagioclase feldspar. Gray shades are most typical.
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Felsic Rocks...
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contain quartz, sodium rich plagioclase feldspar, and potassium feldspar with minor dark minerals. The lightest in color.
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aphanitic texture..
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magma cools quickly and rock consists of very small crystals generally invisible to naked eye
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obsidian texture..
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felsic volcanic glass with dark gray to black color, despite felsic composiiton, lots of dispersed tiny magnetite grains make it dark. Formed at surface of lava flows.
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phaneritic texture...
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magma cools slowly where warm rocks surrounds and insulates it deep beneath the surface, mineral crystals grow very slowly produce this coarse grained texture.
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porphyritic texture...
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magma starts to crystalize slow at depth but moves into colder environment and crystallizes fast. Some large crystals and some small crystals.
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bombs
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largest pyroclastic fragments
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lapilli
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intermediate sized pyroclastic fragments
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volcanic ash
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smallest sized pyroclastic fragments
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ultramafic and phaneritic peridotite composes...
igneous rocks |
Earth's mantle and pieces of this rock are sometimes carried to the surface at erupting volcanoes.
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Basalt and grabbro form from..
igneous rocks |
mafic magma and contain the same minerals but have different textures. gabbro course grained. Oceanic crust composed mostly of these mafic rocks.
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Andesite and diorite
igneous rocks |
solidify from intermediate composition magmas
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Rhyolite and granite
igneous rocks |
form from the most felsic magmas
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Dacite and tonalite
igneous rocks |
have compositions that fall between andesite and rhyolite
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pumice is...
pyroclastic deposits |
lightweight highly vesicular lapilli, dacitic or rhyolite in composition
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cinder is...
pyroclastic deposits |
basaltic or andesitic
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Igneous rocks are used for...
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construction and industry, make good building stone,
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Most volcanoes are found at or near..
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divergent and convergent plate boundaries. Exceptions: hot spots like yosemite
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rock melting depends on..
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temperature, pressure, minerals present in rock, and water
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fractional crystallization
igneous rocks |
the melt changes composition through time because minerals that form early during crystallization differ in composition from the magma and separate from it.
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assimilation
igneous rocks |
magma rises toward the surface comes into contact with the surrounding rock, these rocks might partially or completely mix into the magma, changing it's composition.
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key to understanding volcanic phenomena:
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gas content and viscosity
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viscosity
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resistance to flow
low viscosity = water high viscosity = tar, cake batter |
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basaltic eruptions...
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are usually not explosive and porphyritic
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andesitic, dacitic, and rhyolitic volcanoes
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have more pyroclastic materials than basaltic eruptions, more explosive
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pegmatite
igneous rock |
economically important, forms very late in the crystallization of intrusions, very large crystals, forms from high fluid content. because they crystallize last they are enriched with elements that were excluded from typical rock forming silicates, they are right with rare minerals and exotic elements
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The most common rocks on Earth's surface are...
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sedimentary rocks
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physical weathering: the different processes that make it happen
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water freezing and expanding inside the rock, salt water gets into the rock and then the water dries up leaving salt crystals which break the rock apart, root growth, fluctuating air temps cause minerals to change volume break apart.
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chemical weathering: the processes that make it happen
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dissolution: minerals breaking down into water, hydrolysis- consumes mineral and water molecules while reorganizing elements
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carbon dioxide and water
sedimentary rocks section |
make the most abundant acid in chemical weathering
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oxidation
sedimentary rock section |
process by which substances react with oxygen to form new substances by exchanging electrons.
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clastic sediment
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residue of particles that remain after rocks weather, these particles are the physically weathered parts of the original rock along with minerals such as clays that form by chemical weathering
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Which mineral is the most resistant to weathering?
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Quartz because of it's lack of iron and strong covalent bonds
(silicate minerals are more resistant to chemical weathering) |
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chemical sediment
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most ions dissolved in water eventually precipitate as solid ionic compounds
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how to make a sedimentary rock
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compaction decreases volume of pore spaces and packs grain closer together, stray charges on clay mineral outer surfaces help compact and asymmetry of water molecule. Cementation: pore spaces fill with precipitated minerals that glue grains together; calcite, quartz, clay minerals, hematite the most common.
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how to classify a sedimentary rock
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texture (grain size) composition
clastic, chemical, biochemical (biogenic) |
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sorting
clastic sedimentary rocks |
describes the range of grain sizes. well sorted contains mostly one grain size while poor sorted contains many sized grains
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classification of clastic sediment
clastic sedimentary rocks |
gravel, sand, and mud
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rounding
clastic sedimentary rocks |
angular, rounded
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quartz
arkose and lithic sandstones (clastic sedimentary rocks) |
quartz sandstone is made completely of quartz
arkose sandstone is at least 25% feldspar lithic sandstone consists of sand size rock fragments |
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the most abundant rocks formed by chemical precipitation
chemical sedimentary rocks |
limestone - calcite
chert- quartz most chemical sedimentary rocks are overwhelmingly composed of one mineral |
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rock salt and rock gypsum are commonly referred to as...
chemical and biogenic sedimentary rocks. |
evaporites.
to emphasize formation in arid lagoons or drying desert lakes where evaporation allows precipitation of halite and gypsum |
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clastic sedimentary rocks are as followed:
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breccia- if fragments are angular
conglomerate- if fragments are rounded (gravel) sandstone (sand) mudstone, claystone,siltstone and shale (silt, mud, clay) |
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chemical sedimentary rocks are as followed:
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limestone (calcite)
dolostone (dolomite) chert (quartz) rock salt (halite) rock gypsum (gypsum) coal (plant organic matter) |
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graded beds
sedimentary rocks |
sediment grain size uniformly changes from coarser at the base of a bed to finer at the top
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rocks exhibit two types of metamorphic change...
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new minerals form at the expense of the original ones because of chemical reactions and the rock texture is altered by changes in size, shape, and orientation of minerals
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three processes most commonly cause heat transfer to rocks so they experience high temperature.
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sediment burial
tectonic burial magma intrusion |
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normal stress
and shear stress (metamorphic rocks) |
norman stress is force applied perpendicular to a surface.
shear stress describes force applied parallel to a surface. |
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recrystallization
metamorphic rocks |
is a metamorphic process that changes the size and shape of existing minerals rather than making new minerals (transfer of atoms to one part of a crystal from another part)
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