By: Clara Michael
Types Of Plate Movements & What They Do
Divergent (ocean ) - The plates are pulling away from each other, which causes seafloor spreading, earthquakes & volcanoes. (Ex; Mid Atlantic Ridge)
Divergent (continents) - Plates are being pulled away from each other, creating rift valleys, earthquakes & volcanoes. (Ex; African Rift Valley & Icelandic Rift Valley.)
Convergent subduction - Plates are pushing together, and being pulled down, creating trenches & volcanoes (Ex; Marinas Trench & Ring Of Fire .)
Convergent Continents - Plates are being pushed together, since they have equal densities they are forever upward, creating folded mountain ranges (Ex; Himalayan Mountains.)
Layers Of The Earth & Their importance
Mantle - The "middle layer", is composed mainly of ferro magnesium silcates. This is where most of the internal heat of earth is located. Large convective cells circulate heat and are thought to drive the tectonic plate process.
Crust- The crust is the outer layer of earth, which is basically a thin shell of rock, encasing all the molten heat in the mantle. The crust is mostly made of sedimentary rocks, dirt, sand, and alumio-silcates.
Continental Drift Theory, Evidence, Who created the theory
The original theory was in 1858 Antonio Snider-Pellegrini created two maps demonstrating how America and Africa may have once fit together then separated.
The theory of continental drift is that one point in time, a LONG time ago, all the continents fit together to form one super continent, called Pangaea, but due to plate tectonics, they drifted apart.
Evidence of this theory is that all the continents look like they would fit like puzzle pieces, and also similar fossils found in one continent where found on a different continent.
Sea Floor Spreading, Who Discovered it & How does it explain continental drift.
It's a process that occurs at mid-ocean ridges when new crust forms.
The idea of sea floor spreading was thought by Harry Hess during the 1960's.
It explains & contributes to continental drift because sea floor spreading happens when the plates move apart, which it goes along with the continental drift theory, that the continents moved apart.