Geology Exam 1 - Maps And Plates

Front 1

1cm = ?inches

Back 1

.3937 inches

Front 2

1m = ?feet

Back 2

3.281 feet

Front 3

1km = ?miles

Back 3

.6214 miles

Front 4

1kg = ?lbs

Back 4

2.2046 lbs

Front 5

1 inch = ?cm

Back 5

2.54cm

Front 6

What is the topographical and density difference between continents and oceans?

Back 6

Continental Crust = ~1km of sea level, 2.7 g/cc

Oceanic Crust = ~3.8km below sea level, 3.0 g/cc

Front 7

Who was Alfred Wegener?

Back 7

Theory of Continental Drift.

Matching coastlines etc. to prove continents move across surface.

Not full Plate Tectonics, needed lithosphere

Front 8

What are the compositional layers of the Earth?

Back 8

Core - iron-nickel metal alloy.
Mantle - thick layer of dark green rock.
Crust - very thin layer made of diverse rock types.
Hydrosphere - oceans,glaciers,rivers,etc...
Atmosphere - gaseous outer envelope.

Front 9

Definition of Plate Tectonics

Back 9

The Earth's lithosphere is broken up into a number of plates that move across the Earth's surface.

Front 10

Differences between Outer and Inner Core?

Back 10

Outer Core is liquid Fe-Ni metal that is runny. Slowly crystallizing

Inner Core is a solid ball of crystalline iron-nickel.

Front 11

Divergent Boundaries

Back 11

Two plates pulling apart.

Most common is O-O. Instead of a gap forming, asthenosphere upwells. As it rises, the drop in pressure causes it to melt and fuel volcanoes. (Mid-Ocean Ridge).

C-C = Continental Rifts: creates new thin ocean.

Creates Faults.

Front 12

Convergent Boundaries

Back 12

Plates collide.

Subduction Zones (most common):
O-C: denser oceanic plate forced underneath

O-O: 1 or other ends up underneath. In addition to O-C features, a back-arc basin can form (mini-ocean).

C-C:when an ocean closes up and 2 Continents collide. Causes rocks to pile up (Himalayas). Subducted slab detaches.

Front 13

Ocean-Continent Convergent Boundary features

Back 13

Trench - bent slab along plate boundary
Accretionary Prism - sediment scraped off of the subducting slab. Can rise above sea level to create islands (Barbados).

Volcanic Arc - forms on the overriding plate

Mountain Belt - can form behind the line of volcanoes (Andes)

Front 14

Transform Boundaries

Back 14

2 plates slide by one another.

Usually connected with oceanic divergent boundaries.

O-O, C-C

Front 15

How do pressure and temperature change as you go deeper into the Earth. How do these explain the physical changes in the lithosphere, asthenosphere, and lower mantle?

Back 15

Both temperature and pressure increase.

Lithosphere - rocks are cool and hard.
Asthenosphere - rocks soften, slowly flows, still a solid.
Lower mantle - flows VERY slowly (below 660km).

Front 16

Isostasy definition

Back 16

balance between the downward force of gravity on an object and the upward buoyant force caused by a liquid trying to displace the object.

Front 17

Isostatic equilibrium means...

Back 17

different parts of the lithosphere are floating right where they want to be.

Front 18

What happens when a big load is added on top of continental crust? Removed?

Back 18

A large mass will cause the lithosphere to sag, the more viscous asthenosphere will move away from the area and be displaced by the lithosphere.

Continental lithosphere is thicker and less dense than oceanic.

Front 19

Why does sea floor sink as it moves off the ridge axis and ages?

Back 19

As the asthenosphere cools, it stops flowing and becomes part of lithosphere.

The lithosphere thickens as it moves down the flanks of the ocean ridges = becomes denser.

~10Myr, sea floor dense enough to sink into asthenosphere.

Front 20

Why are convection currents no longer seen as an important driving force in Plate Tectonics?

Back 20

Earth's interior does convect, but calculations suggest that convection is very slow.

Front 21

What 3 forces are thought to drive plate motions?

Back 21

Slab Pull, Slab Suction, Ridge Push

Front 22

Slab Pull

Back 22

Most Important (2x Ridge Push). Fast plate motion.

Ocean lithosphere > 10Myr denser than asthenosphere it is riding on.

Sinks through @ boundary and pulls plate behind it.

Slab experiences inc. pressure. Becuz colder than surrounding astheno., its minerals are forced to compress into denser phases at a shallower depth than those in astheno = Sinks even faster.

Front 23

Slab Suction

Back 23

least important except back-arc basins.

Slab sinks vertically and creates a vacuum that pulls overriding plate.

Creates back-arc basins.

Front 24

Ridge Push

Back 24

Lithosphere slides down slope of top of asthenosphere.

Drives slow plate motions.

Front 25

What is the relationship between earthquakes and plate boundaries?

Back 25

They generally occur along fault lines caused by transform or convergent boundaries.

Irregularities in the fault surface leads to built up stress between the plates until it can finally break through the irregularity and released its built up energy.

Front 26

Where do the majority of earthquakes originate and at what depth?

Back 26

The majority of tectonic earthquakes originate at the ring of fire in depths not exceeding tens of kilometers.

Front 27

Which plate boundary has the most volcanic activity?

Back 27

Convergent Boundaries

Front 28

What is the general relationship between volcanoes and plate boundaries?

Back 28

The oceanic plate subducts under the continental plate forming a deep ocean trench just offshore. Water released from the subducting plate lowers the melting temperature of the overlying mantle wedge, creating magma

Front 29

What topographical feature makes it easy to spot the O-O divergent boundaries?

Back 29

Oceanic-rifts. More shallow in these areas.

Front 30

Along what type of boundary are the deepest places on Earth? What is this feature called.

Back 30

Convergent Boundaries.

Called Oceanic Trenches.

Front 31

What creates tall mountain ranges?

Back 31

Continent Continent Convergent boundaries.

Front 32

Where on Earth is the youngest crust contained?

Back 32

Divergent boundaries

Front 33

How does the depth of earthquakes change moving across a subduction zone? What feature are they tracing?

Back 33

The depth increases and they trace the subducting plate.

Front 34

What is the difference between magma and lava?

Back 34

Magma - molten rock underground. Intrusive rocks.

Lava - molten rock or its cooled equivalent on the surface. Extrusive rock

Front 35

Mafic and Felsic minerals

Back 35

Mafic(Dark): olivine,pyroxene,amphibole,biotite

Felsic(light): plagioclase, k-feldspar,quartz,muscovite

Front 36

Where do intrusive rocks form and what textures do they have?

Back 36

Form under surface and are made of VISIBLE mineral grains that form a coarse-grained texture. Crystalline.

Slow cooling allows elements to migrate to the growing mineral surfaces and keeps mass @ crystallization temperature longer.

Front 37

Where do extrusive rocks form and what textures do they have?

Back 37

Form on surface and contain crystals that are too small to identify.

Fast cooling, causes tiny crystals to form everywhere.

Front 38

What does it mean when extrusive rock has phenocrysts? What is a porphyritic texture?

Back 38

Floating crystals in the fine-grained mass(phenocrysts) create a porphyritic texture.