Science space Flashcards
Earths layers
Compositional Layers:* Crust* Mantle* Core
Mechanical Layers:* Lithosphere* Asthenosphere* Mesosphere* Outer Core* Inner Core
Tectonic plates
- Earth’s crust is cracked into large pieces* These pieces move on the asthenosphere* They are called tectonic plates
Major Tectonic plates
- Eurasian Plate* African Plate* Australian Plate* South American Plate* North American Plate* Pacific Plate
Oceanic plates
Found under the oceans* Thinner and denser
Continental plates
- Found under land* Thicker and less dense
pangaea
- Pangaea was a supercontinent* All current continents were joined together* Existed about 335-175 million years ago
Continental Drift Theory
- Proposed by Alfred Wegener in 1915* Suggested continents were once joined and have moved apart* Initially rejected, accepted in the 1960s
Geographical Evidence
Matching coastlines and mountain ranges
Fossil Evidence
Similar fossils found on different continents
Climatic Evidence
Tillite deposits in unexpected locations
Slab pull
Older, cooler oceanic crust sinks into the mantle* Pulls the rest of the plate along
Ridge Push
New crust formed at mid-ocean ridges pushes older crust away
Convection currents
Particles near heat source gain kinetic energy
Move faster and become less dens Less dense fluid rises
Creates circular motion called convection current
Convection currents and plate movement
Convection currents can speed up or slow down plate movement
Not the main cause of plate movement
Contribute to overall plate tectonic system
Divergent
Plates move away from each other
