Plate Tectonics. The Unifying Theory of Geology. The 4 “Big Ideas” in Geology. The Rock Cycle (Friday’s lecture) By the mid-1700s Antiquity of Earth - “Deep Time” (Wednesday’s Lecture) By the early 1800s, millions of years Faunal Succession (Fossil Record – Core 6) By mid-1800s
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The Unifying Theory
Rather than Young and Static
About 1910, the Mid-Atlantic Ridge was discovered
The study of fossils
Similar fossils in
South America and Africa
The study of ancient climates
All continents have moved to their present positions from one “supercontinent” he called PANGAEA
- 200 Ma
4.5 billion years old
Thousands of drilling samples were taken...
Radiometric dating showed the rocks get older the farther you get from the ridge.
Earthquakes and volcanoes occur mostly along or near trenches and mid-ocean ridges...
The rigid upper 35 miles or so of the earth (lithosphere) is broken up into a dozen or so plates, which can slide around on the zone of weakness.
Current idea: plates move as a result of mantleconvection, driven by earth’s internal heat
Why it’s a
Great trenches and mid-ocean ridges...
Pacific rim trenches and mid-ocean ridges...
“Ring of Fire”
Started forming 400 million years ago (400 Ma)
Started forming 60 Ma
Maroon bells, CO
Started forming 30 Ma
Complex mountain system develops---> Continent Grows
Rocks, Water, Air
Are most likely to contain fossils
Can only be “relatively dated”…
Oceans vs. Puddles
........O H ........
/ \ /
H H ---- O
| | \
O O H .........
/ \ / \
H H H H .........
| | | |
How Earth’s water and air interact ...
Natural “recycling” process
Of natural waters
Layers classified by temperature changes ...
All weather occurs in the troposphere = “churning sphere”
A trenches and mid-ocean ridges...
WEATHER trenches and mid-ocean ridges...and CLIMATE
- Atmosphere Geocycles
Caused by an unattached atmosphere over a rotating Earth
ACTUAL trenches and mid-ocean ridges...
OCEAN CURRENTS trenches and mid-ocean ridges...