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Earth Science Test 2 Review
Earth Sciences for non majors at Collin College Test 2 review
Terms in this set (60)
Luster is the property of minerals that shows how much or how well the mineralreflects light. Non-metallic, or sub-metallic luster includes waxy, pearly, silky, vitreous, greasy, resinous, dull, and adamantine
The streak of a mineral is the color of the powder produced when it is dragged across an un-weathered surface.
In mineralogy, crystal habit is the characteristic external shape of an individual crystalor crystal group
Tenacity describes the reaction of a mineral to stress such as crushing, bending, breaking, or tearing.
The degree of hardness is determined by observing the comparative ease or difficulty with which one mineral is scratched by another or by a steel tool.
cleavage vs. fracture
Fracture is the characteristic way a mineral breaks. The difference between cleavageand fracture is that cleavage is the break of a crystal face where a new crystal face is formed where the mineral broke, whereas fracture is the "chipping" of a mineral.
mineral that reacts to acid
structure of the atom
Atoms consist of three basic particles: protons, electrons, and neutrons. The nucleus(center) of the atom contains the protons (positively charged) and the neutrons (no charge). The outermost regions of the atom are called electron shells and contain the electrons (negatively charged).
Covalent bonds are very strong bonds formed when atoms share electrons with neighboring atoms. Sulfur, and both of carbon's natural forms, graphite and diamond, are covalently-bonded minerals. So is quartz, which contains only silicon and oxygen.
In the mineral halite, NaCl (common, or rock, salt), the chemical bonding that holds the Na+ and Cl− ions together is the attraction between the two opposite charges. Ionic bonding is the complete transfer of valence electron(s) between atoms.
Metallic bonds are generally weaker than either covalent or ionic bonds, which explains why metallically bonded minerals (true metals), like silver, gold, and copper, can be worked—beaten into flat sheets, or drawn into thin wires.
Rock forming mineral groups
The most common rock-forming minerals are silicates (see Vol. IVA: MineralClasses: Silicates), but they also include oxides, hydroxides, sulfides, sulfates, carbonates, phosphates, and halides
difference between lava and magma
lava: molten rock above the earth's surface
magma: molten rock below the earth's surface
Igneous Rock Classification: texture
course grained, fine grained, porphyritic, glassy, vesicular, pyroclastic
Igneous Rock Classification: composition
Granitic (Felsic) - mainly quartz and potassium feldspar (pink)
Andesitic (Intermediate) - Amphibole and plagioclase feldspar (blue gray)
Basaltic (Mafic) - Pyroxene and plagioclase feldspar
Ultramafic - Olivine and Pyroxene (Dark gray/green)
Igneous Rock Classification: formation
Intrusive (plutonic) - cool slowly below the surface
Extrusive (volcanic) - cool quickly on the surface
Mechanical weathering and its role in the rock cycle
Mechanical weathering breaks rock into smaller pieces. These smaller pieces are just like the bigger rock, just smaller. ex. Ice wedging and abrasion
Chemical weathering and its role in the rock cycle
Chemical weathering is different from mechanical weathering because the rock changes, not just in size of pieces, but in composition. Chemical weathering works through chemical reactions that cause changes in the minerals. ex. hydrolysis, acid rain, oxidation
Breaks rocks down to sediment
Detrital Sedimentary Rocks
made from broken fragments of other rocks
chemical sedimentary rock
Chemical sedimentary rock forms when mineral constituents in solution become supersaturated and inorganically precipitate. Common chemical sedimentary rocksinclude oolitic limestone and rocks composed of evaporite minerals, such as halite (rock salt), sylvite, baryte and gypsum.
Biochemical sedimentary rocks
Biochemical sedimentary rocks are formed from organic processes that involve living organisms producing the sediments. These living organisms can be snails and clams whose discarded calcium carbonate shells can form limestone
organic sedimentary rock
Organic sedimentary rocks are those containing large quantities of organic molecules
Types of Metamorphism: contact vs. regional
Contact metamorphism is a type of metamorphism where rock minerals and texture are changed, mainly by heat, due to contact with magma.
Regional metamorphism is a type of metamorphism where rock minerals and texture are changed mainly by pressure over a wide area or region. ex. tectonic plates converging
Lithosphere vs. asthenosphere
The lithosphere is the brittle crust and uppermost mantle. The asthenosphere is a solid but it can flow, like toothpaste. The lithosphere rests on the asthenosphere.
Wegener's super continent
Pangaea. Theorized in 1910
Opposition to Wegener's Theory
The main objection to Wegener's hypothesis was from his inability to identify a credible mechanism for continental drift.
Evidence supporting plate tectonics
jig saw puzzle, fossils, seismic volcanic and geothermal energy along the boundaries,
Mid Atlantic Ridge - plates being torn apart
Himalayas - plates being pushed together
Layers of Earth: crust, mantle, core, lithosphere, asthenosphere
- Earth's crust is a thin shell on the outside of Earth, accounting for less than 1% of Earth's volume.
- The Earth's mantle is a layer of silicate rock between the crust and the outer core. It makes up 67% of the mass of the Earth. It makes up about 84% of Earth's volume.
- The lithosphere is the solid, outer part of the Earth. The lithosphere includes the brittle upper portion of the mantle and the crust, the outermost layers of Earth's structure.
- The asthenosphere is the denser, weaker layer beneath the lithospheric mantle. The temperature and pressure of the asthenosphere are so high that rocks soften and partly melt, becoming semi-molten.
Plate Boundaries and what they create (rift valleys, mountain ranges, volcanic arcs, earthquakes etc.)
collide - convergent boundary forms deep trenches and volcanoes
move away - divergent - creates new crust and submarine volcanic mountain ranges
slide - transform - earthquakes and faults - San Andreas Fault
specific formations created by these boundaries Types of Convergent boundaries What happens in subduction zones
Subduction zones (where one plate goes underneath another) create volcanoes
Age of ocean basins
200 million years
Hot spots and examples, what they tell us
volcanic regions like Hawaii, Yellowstone,
A hotspot's position on the Earth's surface is independent of tectonic plate boundaries, and so hotspots may create a chain of volcanoes as the plates move above them.
Mechanism for plate movement
convection deep in the earth
Types of volcanoes and examples of each
Cinder cones - build a blob until pressure explodes
composite - steep sided - lava cinders ash lava cinders ash
Volatiles in magmas- most abundant gasses
volatiles are dissolved gasses
water vapor, carbon dioxide, sulfur dioxide, hydrogen sulfide and hydrogen halides
Viscosity and how it affects magma in volcanoes
the thinner the magma the more flow it is
the thicker magma clumps and explodes under pressure
AA, Pahoehoe lavas
AA - thick magma - The surface of the aa flow consists of free chunks of very angular pieces of lava.
pahoehoe - ropey and thin runny lava like ketchup
Region of world with the most volcanic activity
indonesia - pacific ring of fire
Plutons, batholiths, loccoliths
a pluton is a body of intrusive igneous rock that is crystallized from magma slowly cooling below the surface of the Earth.
A batholith is a large pluton mass of intrusive igneous rock, larger than 100 square kilometres in area, that forms from cooled magma deep in the Earth's crust.
A laccolith is a sheet-like intrusion that has been injected within or between layers of sedimentary rock. The pressure of the magma is high enough
Catastrophism vs. Uniformitarianism and age of the earth
1600s - Catastrophism was based on the idea that major features of the earth were created by catastrophes or disasters of unknowable causes. 6000 yrs old
Today - Uniformitarianism states that the physical, chemical and biological laws that operate today also operated in the past. 4.5 billion yrs old
Principals of Horizontality, lateral continuity, inclusions, cross-cutting
The Principle of Original Horizontality states that layers of sediment are originally deposited horizontally under the action of gravity.
The principle of lateral continuity states that layers of sediment initially extend laterally in all directions; in other words, they are laterally continuous.
The principle of cross-cutting relationships states that an igneous intrusion is always younger than the rock it cuts across
relationships, superposition- Why are these important?
This is important to stratigraphic dating
Types of unconformities; what they are, how they are formed
break in the even layers by a break of an eroded layer and a deposition on top
Non parallel strata - flat strata on top of diagonal - layers go under pressure and are folded and then erosion occurs and then another layer is deposited.
Relative Dating vs. Absolute Dating
Absolute dating is based off of half lives
Relative dating is based off of fossils and laws of super position
How fossils form
Specimen is buried by sediment, more layers accumulate and minerals like silica replace calcium phosphate in bones, fossils are pushed to the surface, and erosion or digging expose the fossil.
Types of Fossils
Cast or Mold - A mold preserves a negative imprint of the surface, while a cast prserves the external form of the organism.
Replacement - water dissolves the hard parts of the organism and replaces them with minerals
Per mineralization - Pore spaces are filled in with minerals - fossilized wood
Carbonization - A carbon residue is left on a rock from the organic material of the animal or plant
Imprint - A replica of the surface of a fossil
used to define and determine geologic time
Correlation of Strata
comparing the physical characteristics of strata with each other (physical correlation); and by comparing the type of fossils found in various strata (fossil correlation).
Isotopic Dating- Types used for different ages
dating using decay rates of certain minerals.
Age of the Earth
4.5 billion years
Divisions of Geologic time scale: Eon, Era, Period etc. Know order.
Eon, Era, Period, Epochs, and stage/Ages
Oldest rocks on Earth and how we date them
felsic rocks 2.5-3.8 billion years
we use radiometric dating
Continental vs. Oceanic Crust
continental - 40 km
oceanic - 6 km
Cratons and Shields
A craton is an old and stable part of the continental lithosphere
A shield is a large area of exposed Precambrian crystalline igneous and high-grade metamorphic rocks that form tectonically stable areas.
Super Continent before Pangaea and its age.
Pannotia 600 million years ago
a process in which a section of the earth's crust is folded and deformed by lateral compression to form a mountain range.
Two parts of Pangaea (Northern and Southern)
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