earth science- midterm 1

Diamond and graphite

Different types of carbon bonding

Earth's magnetic field

Generated by the outer core

Age of Earth

Approximately 4.6 billion years

Scientific theory

Not a conjecture or guess

Earth's outermost rigid layer

Lithosphere

Moon formation

Protoplanet collision with Earth approximately 4.5 billion years ago

Lithospheric plates

Collide during convergent boundaries

Shield volcano

Does not have large explosive pyroclastic eruption

Low viscosity volcanoes

Have low SiO2 content and fast flows

Volcanic structure

Determined by pillow and pahoehoe flows

Basaltic and rhyolitic lava

Have incorrect viscosity statement

Most abundant minerals in basalt

Plagioclase and pyroxene

Basalts

Typically have an aphanitic texture

Fast cooling of magmas

Tends to produce an aphanitic texture

Phenocrysts in porphyritic texture

Do not reflect fast cooling

Basalts

Not the most common intrusive rocks on Earth

Glassy textures

Not a product of lower nucleation and higher growth rates than aphanitic textures

Phaneritic textures

A product of lower nucleation and higher growth rates than aphanitic textures

Igneous texture in photo

Pyroclastic

Igneous texture in photo

Porphyritic

Properties of minerals

Indicate crystal structure and chemical composition

Most minerals

Belong to the silicates class

Plane where minerals split

Cleavage plane

Covalent bond

Electrons are shared between all atoms in a solid mass

Softest and hardest minerals on Mohs' hardness scale

Talc and diamond

Colour as a diagnostic property of minerals

False

Chemical formulas for erite-olivine and quartz

NaCl and CaCO3

Chemical formulas for Nayalite-olivine and calcite

Fe2SiO2 and CaCO3

Most abundant mineral in the crust

Pyroxene

Chemical formulas for albite and anorthite plagioclase

NaAlSi3O8 and CaAl2Si2O8

Chondrites

Oldest known rocks in the solar system (True)

Granite pluton and fault

Granite pluton is older than the fault (True)

Parent to daughter ratio after 200 million years

1/4

Parent/daughter isotope ratio after three half-life times

1/7

Remaining parent isotopes after three half-life times

150

Change in proton number after nucleus captures four electrons

Decrease four

Change in proton number after four alpha decay

Decrease eight

Change in proton number after two alpha decay

Decrease eight

Sill and sandstone layer

Sill is older than the sandstone layer (#5) (True)

Process of creating new seafloor, moving away from ridges, and subducting

Sea-floor spreading

Glaciers and 18^O/16^O ratios

Glaciers do not have higher ratios than seawater

Negative magnetic anomaly

Does not form when seafloor rock polarity is the same as the present magnetic field

First scientist to propose continental drift hypothesis

Alfred Wegener

Andes and Pacific Ocean plate boundary

Convergent boundary

Supercontinent united about 300 million years ago

Pangea

Youngest to oldest magnetic epochs (chrons)

Brunches, Matuyama, Gauss, Gilbert

Earth's magnetic poles

Do not regularly reverse every 1.5 million years along mid-ocean ridges

Magnetic inclination angles

Vary along latitude lines

Magnetic inclination angles

Not highest at the equator

18^O/16^O in seawater

Increases during ice ages

Seawater and rainwater

Seawater does not have lower 18^O/16^O ratios

Mantle plumes

Originate below the lithosphere