GEL 16 Lecture 2: Geology Notes
Geology Notes – 10/2/17 Lecture #2
4.56 bil
Felsic- makes up most continent
Mafic-Ocean
Radius of the earth= 6371km
Rheology: not talking about the crust anymore, but composition of earth defined based on layer
behavior
-Lithosphere= brittle
Incorporates part of upper mantle
All crust, upper mantle
-Asthenosphere=ductile (behaves like heated plastic)
Also represets the upper atle ut ot the etire part, just the upper part thats hotter
-Boudary of Lith/Astheosphere= Moho
(Review page 21 on lecture 2)
-The lithosphere floats o the astheosphere ad is oposed of to kids of rust.
-Concept called isostasy: uoyay of Earths rust floats at a eleatio that is related to its thikess
and density
Plate Tectonics
-unifying theory of geology
-Tectonics: movement of the crust
-Plate Tectonics: Movement of discrete segments (plates) of the crust in relation to each other
Note: Not all faults are plate boundaries, plate motion not driven by faults
Alfred Wegener: Continental Drift
- Supercontinent Pangaea, single ocean Panthalassa, 5 pieces of evidence:
- 1. Fit of the continents (puzzle pieces)
- 2. Glacial Till (remains that gets left behind when a glacier melts)
o Glacial features: polish and striations, Glacial till, characteristically coarse unsored
- 3. Fossil Distributions (made this observation since we found fossils around the same age and
same thing found in different parts of the world)
- 4.Paleoclimate inferred from deposits (rocks are good are recording climate)
- 5.Geological formations
- Breakup of Pagaea
o 200-250 million years ago
o Split to form Laurasia and Gondwanaland
o Continued to split to for continents we have today
How do we know the Earth has plates? How do we know they move?
-plate tectonics does not equal continental drift, be able to define separately
- Magnetic readings help us understand
- WWII and WWII Sea floor exploration
-Harry Hess (first person to come up with idea of se floor spreading)
-Young Ocean Crust – oldest crust is in W. Pacific, oldest is 200Ma
-Seafloor spreads at MOR
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Rheology: not talking about the crust anymore, but composition of earth defined based on layer behavior. Also represe(cid:374)ts the upper (cid:373)a(cid:374)tle (cid:271)ut (cid:374)ot the e(cid:374)tire part, just the upper part that(cid:859)s hotter. Bou(cid:374)dary of lith/asthe(cid:374)osphere= (cid:862)moho(cid:863) (review page 21 on lecture 2) The lithosphere (cid:862)floats(cid:863) o(cid:374) the asthe(cid:374)osphere a(cid:374)d is (cid:272)o(cid:373)posed of t(cid:449)o ki(cid:374)ds of (cid:272)rust. Concept called isostasy: (cid:271)uoya(cid:374)(cid:272)y of earth(cid:859)s (cid:272)rust (cid:858)floats(cid:859) at a(cid:374) ele(cid:448)atio(cid:374) that is related to its thi(cid:272)k(cid:374)ess and density. Plate tectonics: movement of discrete segments (plates) of the crust in relation to each other. Note: not all faults are plate boundaries, plate motion not driven by faults. 4. paleoclimate inferred from deposits (rocks are good are recording climate) Breakup of pagaea: 200-250 million years ago, split to form laurasia and gondwanaland, continued to split to for continents we have today. Plate tectonics does not equal continental drift, be able to define separately. Young ocean crust oldest crust is in w. pacific, oldest is 200ma.
