Warmup What was the large ancient landmass called? (Get a textbook from off the shelf and 2 pieces of decorative/construction paper)

Pangea!

Plate Tectonics

Layers of the Earth by composition

by physical properties Lithosphere- the outermost, rigid layer that is divided into pieces called tectonic plates Asthenosphere- the plastic layer of the mantle on which pieces of the mantle move. Mesosphere- strong, lower part of the mantle between the asthenosphere and the outer core. Outer Core- the liquid layer of the Earth’s Core Inner Core- a solid, dense center of our planet.

Continental Drift It all started (well, finished, sort of…) with a German meteorologist, Alfred Wegener He presented his theory in 1912 All the continents were once joined as one great landmass, Pangaea! They had moved or drifted to their current positions over millions of years.

“The Origin of Continents and Oceans” Published in 1915 Rejected and ridiculed by geologists – what force could possibly move such large land masses!

Continental Drift The continents are plowing through the ocean floors Africa & South America look like they fit together similar fossils, rocks, and glacial striations Similar fossils = correlation!!! (Geologic time notes!)

The earth moves… http://www.tectonics.caltech.edu/outreach/animations/anim_pangaea/Resources/anim_pangaea.mov

How did Wegener know this? In modern times, we can easily measure the amount of movement in the continents. We can use GPS and other modern technologies. In 1912, Wegener had no computer, just his logical brain. He used the evidence he found in geology and fossil records to theorize what we now know to be true: the continents shift.

The fossil record for some very old organisms…

And there’s coal…in…Antarctica? Now, just a minute! Coal is formed from equatorial, jungle plants, pressure, and heat…how did coal end up in Antarctica? The theory (and remember where theory fits in the hierarchy of science?) is that the coal in Pennsylvania also originated at the equator! Wegener realized that no other explanation could make sense of the coal in frozen areas.

Glaciers…in…Africa? No way! He also found evidence of glacial deposits in sweltering Africa!

Continental Drift…Accepted! In 1960’s, new technology showed indisputable evidence that the seafloor in the Atlantic Ocean is spreading! Harry Hess, WWII Navy Captain – evidence the ocean crust moves!

These are the plates…

An extreme close-up: What are the highest mountains in the world? Where are they in relation to this picture? Did you know they’re still growing? (about 5 mm / year) Mount Everest---border of China and Nepal (just north of India!)

Plate Tectonics Oceanic plate- thin plate with high density Earth's crust is made up of plates that ride on top of the asthenosphere The plates move due to convection currents in the mantle Oceanic plate- thin plate with high density Continental plate- thick plate with low density

Plate Boundaries Divergent plate boundary- the boundary formed from the separation of two lithospheric plates Oceanic-Oceanic: mid ocean ridge Continental-Continental: Rift Valley

Convergent plate boundary- the boundary formed from the collision of two lithospheric plates O-O: volcanic island arc O-C: volcanic arc C-C: mountains

Transform plate boundary- the boundary formed from the sliding of two lithospheric plates past each other in opposite directions