Geology 211 First Exam Wwu

Front 1

What is the geologic time scale? (GTS)

Back 1

A system of measurements that use the layers of rocks in the earth to measure time and events in Earth's history.

Front 2

What is the age of the earth?

Back 2

4.543 billion years

Front 3

Define Uniformitarianism

Back 3

The theory that the earth of today was formed through normal geological process occurring throughout the expanse of the planet's lifetime (erosion, earthquakes, volcanoes, etc...)

Front 4

List the layers of Earth

Back 4

Crust, mantle, outer core, inner core

Front 5

What are the asthenosphere and lithosphere?

Back 5

Lithosphere contains the crust and the cool rigid part of the upper mantle. (Brittle)
The asthenosphere contains the lower mantle.(Plastic)

Front 6

Describe the history of the Continental Drift theory.

Back 6

Alfred Weigner's theory that the continents of the earth were moving through the ocean to explain why there were similar rocks, fossils, and geologic structures on continents across the world, but his ideas were rejected since he wouldn't explain how they moved. Years later two geologists (harry hess & robert dietz) created a new theory called "Seafloor spreading" to explain the movement of the continents.

Front 7

What is "Seafloor Spreading"?

Back 7

The theory that the continents move across the earth due the the ocean crust spreading at mid-ocean ridges. This is also how new oceanic crust is formed.

Front 8

Where is the Pacific Plate and what are some of its geologic characteristics?

Back 8

The pacific plate lies in the Pacific Ocean and is the largest crustal plate on Earth. It's moving in a general NW direction and contains landmarks like the "Ring of Fire" and the "Mariana Trench".

Front 9

Where is the North American Plate and what are some of its geologic characteristics?

Back 9

The N American Plate lies in the northern hemisphere and is big.

Front 10

What the difference between oceanic and continental lithosphere?

Back 10

The oceanic lithosphere is thin, young and dense (basalt), while the continental is thick, old, and less dense (various rocks).

Front 11

What do divergent plate boundaries in the ocean tend to cause?

Back 11

Mid ocean ridges: "spreading centers" that create new lithosphere

Front 12

Explain the process that creates mid ocean ridges.

Back 12

As the plates move apart solid mantle begins to rise up through the asthenosphere which melts due to pressure change and becomes magma. The magma rises and forms magma chambers which send up magma to cool and become part of the oceanic lithosphere. The magma that erupts and cools on the surface becomes new crust.
The rift forms when large blocks of crust fall down though the spreading from the plates.

Front 13

What are the characteristics of fast vs slow mid ocean ridge spreading rates?

Back 13

Slow spreading rates result in a rugged topography and a wide deep valley, while fast spreading has a higher valley and has gradually rising flanks.

Front 14

Explain the process of continental rifting

Back 14

As the continents diverge manga pushes up through the crust which in turn heats up the crust creating a rift. Large pieces of the crust fall down along the faults creating a valley on the surface that can accumulate water forming a lake. Magma may also erupt from volcanoes/ fissures and as the crust thins the valley becomes wider and deeper.
Eventually the valley may form a basin and eventually an ocean of the rift becomes deep and wide enough.

Front 15

What creates Island Arcs?

Back 15

Magma erupts from convergent ocean boundaries and forms undersea volcanoes. If they continue to be active eventually they form an island arc.

Front 16

Whats the difference between an island arc and an island chain?

Back 16

An island arc is formed at plate boundaries through subduction, while an island chain is formed from a plate passing over an active hot spot

Front 17

What is a mantle plume?

Back 17

When exceptionally hot rock rises up in the mantle and creates a hot spot.

Front 18

How do you calculate the rate of seafloor spreading?

Back 18

Rate of spreading = width of stripe / Time duration

Front 19

How do we measure plate movement?

Back 19

Global Positioning Systems (GPS)

Front 20

What type of plate movement creates the largest earthquakes?

Back 20

Convergent plate boundaries.

Front 21

What is a silicon-oxygen Tetrahedron composed of?

Back 21

4 Oxygen atoms and 1 small silicon atom shaped like a pyramid (a tetrahedron) around the silicon.

Front 22

How do minerals form crystals?

Back 22

They either melt into magma and then cool and form crystals under the surface or above, or dissolve in water then reform as crystals upon cooling.