GEO Exam 1 review

How is Earth's magnetic field generated?

Flow in the liquid outer core

Which of the following observations is not consistent with Uniformitarianism?

A series of global catastrophes during the past 6,000 years are responsible for the current distribution and composition of all rocks on the Earth’s surface

Name Earth's compositional layers (1–4)

Crust; Mantle; Outer core; Inner core

Which Earth's sphere contributes to rock/mineral color through oxidation?

Atmosphere

How do the rock types primarily form?

Igneous: Crystallization; Sedimentary: Lithification; Metamorphic: Deformation

Which statement best describes the asthenosphere?

The hot, weak layer of the Earth that flows via convection and drives plate tectonics

Which rock type forms at surface and subsurface?

Igneous

How do we know the Earth has a liquid outer core?

Seismic wave evidence

Current accepted age of Earth

4.6 billion years

Which is NOT a method to depict subsurface features?

Geologic maps

Difference between elevation and relief

Elevation = height above sea level; Relief = difference in elevation

Microscopic-scale geologic feature

Thin section

Steps of the scientific method

Make observations; Form hypothesis; Test hypothesis; Develop theory; Re-test/re-examine

Tectonic boundary along west margin of South America

Ocean-continent convergent

NOT evidence for Continental Drift

Age of the seafloor

Hazards at convergent boundaries

Earthquakes and volcanic eruptions

Boundary at location C on diagram

Transform boundary

Oldest vs youngest seafloor

The oldest is at B; the youngest is at A

Boundary setting for hotspot island chains

None; they occur within plates

Boundary that joins convergent & divergent

Transform

Boundary influenced by crust density

Convergent

Earthquake pattern: which plate subducts?

The Nazca Plate is subducting beneath the South American Plate

Three chemical layers of Earth

Crust; Mantle; Core

Phenomenon NOT explained by plate tectonics

Geomagnetic reversals

Where would volcanoes be found in diagram?

Location B on overriding South American Plate

Single tetrahedra bonded to Fe/Mg group

Olivine group

Which is NOT a mineral?

Coal

Most common crustal minerals

Having a framework of silicate anions

Mineral with hardness 7, vitreous, conchoidal

Quartz

Charge on individual silica tetrahedra

-4

Elements making up ~75% of continental crust

Silicon and oxygen

NOT a silicate mineral

Galena

What determines cleavage & luster?

Types of bonds at molecular level

An element is defined by

Number of protons

Elements in high-density minerals (olivine/pyroxene)

Iron and magnesium

Double-chain tetrahedra group

Amphibole

Part of atom involved in bonding

Outer electron shell

How geologists test hardness/specific gravity/streak

Mohs scale; measure density; powder the mineral

Phaneritic texture description

Visible crystals of similar size in an igneous rock

Factors determining magma composition and behavior

Tectonic setting; Silica content

Lowest vs highest melting point minerals

Olivine (low); Quartz (high)

NOT a compositional igneous class

Ultrafelsic

Fractional crystallization of mafic magma

Evolves toward felsic composition

Intrusive equivalent of rhyolite

Granite

Melting at mid-ocean ridge

Decompression melting

Texture showing two crystallization stages

Porphyritic

Igneous rocks distinguished by

Composition and texture

Factor influencing crystal size

Rate of cooling

Igneous rocks in volcanic arcs

Intermediate

Implication of Bowen’s Reaction Series

Magmatic liquids continually change composition

Mechanisms of partial melting

Adding heat; Decompression; Adding water/volatiles (flux)

A caldera is…

Associated with collapse, ring fractures, and huge pyroclastic flows

How we measure eruption magnitude

VEI

Partial melt process in volcanic arcs

Flux melting

NOT a cause of volcanic eruptions

Magma is more dense than surrounding rocks

Utah's famous igneous intrusions

Laccoliths

NOT a volcanic hazard

Lava tubes

Volcano type erupting full range (mafic→felsic)

Stratovolcano

Largest igneous intrusions

Batholiths

NOT a setting where magmatism occurs

Transform boundaries

Eruptions tied to mass extinctions

Flood basalts

NOT a reason for different eruption types

Climate

Volcano with low-volatile basalt eruptions

Shield volcano

Parameters controlling eruption type

Viscosity; Composition; Volatile content; Temperature