GEOG 1266 Lecture Notes - Lecture 2: Deep Sea Drilling Project, East African Rift, Continental Crust
13 Jun 2018
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Department
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PLATE TECTONICS
1) HISTORICAL DEVELOPMENT OF IDEAS
a) Alfred Wegener (1880-1930) – German scientist/Meteorologist primarily worked
in the arctic. Well read about glaciers.
b) Fossil records are key in determining time periods of ice
c) Wegner – Pangea – Proposed the idea of continental drift – The continents
moved through oceanic crust. Ridiculed for his radical claim.
d) Deep sea drilling program 1968 – Drilling sediment cores – gave more evidence
of continental drift
e) Spreading Center/Ridge- Crust moves with newest crust in the middle and the
oldest peeling away from ridge.
f) Marianas Trench – Deepest Trench 10,000 m. Related to tectonic theory
g) Primary Tectonic Plates – Pacific plate, north American, African, Eurasian,
Arabian plate, etc.
2) PLATE COMPOSITION
a) Continental crust and oceanic crust move together
b) Km
0
10 (Oceanic) Crust (Continental)
PLATE
Upper Mantel
100
Asthenosphere
DENSITY
CHEM COMP
PHYSICAL
CHARACTERISTICS
CRUST
Continental
2.7
Felsic
Solid, Brittle
Oceanic
3.0
Mafic
Solid, Brittle
UPPER MANTLE
3.3-5.0
Ultra-Mafic
Solid, Brittle
ASTHENOSPHERE
3.3-5.7
Ultra-Mafic
Solid, Plastic
3) PLATE BOUNDARIES
a) DIVERGENT Continental Crust Continental Crust
i) Rift Zone
East African Rift Valley
Magma
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