Chapter 4 Tectonic Plates

Question 0

Accretionary prism

Answer 0

Forms in a convergent/ subduction zone. As subducting plate goes down the sediment from it gets pushed up.

Question 1

Volcanic arc

Answer 1

Develops behind a accretionary prism .

Question 2

East African Rift Valley

Answer 2

Divergent boundary. If continues one day Africa continent will be in separated.

Question 3

Thomas Kuhn

Answer 3

“Scientific Revolution”

1960s, historian of science. Says scientists base there interpretation of the natural world by reasoning and their experiences.

Question 4

Plate tectonics. Who made previous research.

Answer 4

Tectonics theory evolved in the 1960s.
Wegner(1915) evidence supporting continental drift.
Hess/dietz (1960) the sea-floor spreading hypothesis.

Question 5

Geologists adopted…

Answer 5

Tectonics theory by 1968, evidence was overwhelming.

Question 6

Harry Hess and Robert Dietz’s

Answer 6

Proposal that sea floor is spreading

Question 7

Lithosphere

Answer 7

Consists of the crust plus the uppermost (coolest) part of upper mantle. Acts elastically, bends, flexes and sometimes breaks. Floats on the asthenosphere.

Question 8

Asthenosphere

Answer 8

Warmer mantle that can flow when acted in by force.

Question 9

Continental and oceanic lithosphere.

Answer 9

Differ in thickness. Continental =150km
Old Oceanic =100km
New oceanic crust = 7 to 10 km

Question 10

Principle of buoyancy

Answer 10

Floating solids displace water equal to their mass.

• and iceberg “sinks” until the mass of water it displaces is equal to the total mass of the iceberg.
• concept applies to lithospheric plates.

Question 11

How many plates make up lithosphere?

Answer 11

20 tectonic plates. Plates move continuously at a rate of 1-15cm/yr.
They come in a variety of sizes and shapes. They can change shape and size throughout their history.
-

Question 12

Plate Boundaries

Answer 12

Where tectonics plates meet.
- identified by concentration of earthquakes.
- associated with many other dynamic phenomena.
- plates interiors are almost earthquake free.
-

Question 13

Continental Margins

Answer 13

Where land meets ocean. Margin near plate boundaries are active.
- margins far from plate boundaries are passive
-

Question 14

Divergent boundary

Answer 14

Tectonic plates move apart.

• lithosphere thickens away from the ridge axis
• aka spreading boundary, mid-ocean ridge, ridge

Question 15

Convergent boundary

Answer 15

Tectonic plates that move together. Called subduction. Plate consumption. Aka convergent margin, subduction zone, trench

Question 16

Transform boundary

Answer 16

Tectonic plates slide sideways.
Plate material is neither created not destroyed. Aka transform fault. Slip parallels the earths surface. San Andrés fault last time was districting was in 1906.

Question 17

Triple junctions

Answer 17

Where tree plate boundaries intersect at a point. Ex: southwest Indian Ocean ridge intersects two arms of mid-Indian ocean ridge (African, Antarctica and Australian plates)
These plate boundaries can be ridges and transforms

Question 18

Plate-boundary volcanoes

Answer 18

Subaerial volcanoes (above sea level) at volcanic arcs that border trenches. Most submarine volcanoes (underwater) lie given along mid-ocean ridges. Formed as a consequence of movement along boundary.

Question 19

Hot spring

Answer 19

Volcanoes that are located in the interiors of plates away from the boundaries but some are straddle mid-ocean ridges

Question 20

Pg 104 deep plum mantle model for hot spots good to write in the term paper.

Answer 20

Canadian geologist . End of pg 104 Yellowstone national park is brought up.

Question 21

Relative plate velocity

Answer 21

Comparing the movement of two plates.

Question 22

Absolute plate velocity

Answer 22

Describe movement of two plates relative to a fixed point in the mantle

Question 23

Global Positioning System (gps)

Answer 23

Geologists use an array of GPS receivers to monitor plate displacements of millimeters per year.

Question 24

Volcano

Answer 24

A vent where molten rock comes out of earth.