Term
CONTINENTAL CRUST
Makes up how many percent of the earth?
?~? km thick?
What is its composition? |
|
Definition
30% of earth at 2.7g/cm3
35-70km thick
Composition averages Intermediate to felsic. |
|
|
Term
OCEAN CRUST
Makes up how much percent of the earth?
?~? km thick?
Compostion? |
|
Definition
70% of earth at 3.0g/cm3 (oceans)
6-7 km thick
Mafic (basalt) |
|
|
Term
EVIDENCE FOR PLATE TECHTONICS
Continental drift was suggested by Alfred Wegener in 1915. What did he propose? |
|
Definition
1) Continents joined in pangaea. (supercontinent)
2) Pangaea broke apart in the Mesozoic, and the continents drifted to present positions.
His Evidence was:
*Jigsaw puzzle fit of continents
*distrubution of fossils (plants & animals)
*how rocks and mountain belts match up across the continents. |
|
|
Term
SEA FLOOR SPREADING
What is the evidence for sea floor spreading? |
|
Definition
*Mid ocean ridges/MORs (mountains)
*Abyssal plains- Deep flat areas
*Trenches 8-12km deep. |
|
|
Term
| What type of igneous rocks will line up with earths magnetic field? |
|
Definition
Igneous rocks with Iron and Magnesium.
(magnetometer:studies rocks on the bottom of the ocean/ground) |
|
|
