- There were one scientist who looked at the pieces of puzzle wad Alfred Wegener.
- 1900s- he wrote hypothesis about continental drift.
- Continental drift also explains why fossils of plants or animals same found on many different places.
- Continental drift is the hypothesis that states that the continents once formed a single landmass, broke up and drifted to their present location.
Pangaea
- 245 million years ago.
- Pangaea existed
- Was surrounded by a sea named panthalassa.
- 180 years ago.
- Pangaea broke into two big parts
- northern- Laurasia
- southern-Gondwana
- 65 million years ago.
- Dinosaur extinct.
- Laurasia and Gondwana split into more smaller pieces.
Sea-Floor Spreading
- Mid-Ocean Ridges and sea-floor spreading
- Mid-underwater mountain chains that runs through Earth`s ocean basins.
- The process of which new oceanic lithosphere(crust) forms as magma that rises toward the surface and solidifies.
- if tectonic plates move apart from each other, the sea floor fills with magma.
- After the new crust forms, old crust gets pushed away from Mid-Ocean ridge.
- Evidence of sea-floor spreading comes from magnetic reversals.
- early history-north./south magnetic poles changed for many times.
- Magnetic poles change, called magnetic reversal.
Plate tectonics
- Plate tectonics- the theory that explains how large pieces of earth`s crust change shape and move.
- Convergent boundary- formed by a collision of two lithosphere plates.
- Divergent boundary- when two tectonic plates move away.
- Transform boundary- when two tectonic plates slide past each other horizontally.
Possible movements of tectonic plates.
- Ridge push- Because the oceanic lithosphere is higher than it is, it slides down under the force of the gravity.
- Slab pull-edge of the tectonic plate that contains oceanic lithosphere, it pulls tectonic plate. Because oceanic lithosphere is denser than asthenosphere.
- Convection-causes the oceanic lithosphere move sideways and away from the mid-ocean ridge.
GPS- Global Positioning System.
Deformation
- Compression-squeezed;two tectonic plates collide. ;If compression occurs at a convergent boundary, large mountains can form.
- Tension-force act to stretch an object; two tectonic plates gets apart.
- Volcanic mountains-convergent area; convergent boundary sinks into asthenospere at subduction zone.
Faulting
- : A break in a body of rocks which slides relative each another.
- Normal faults- occur when tectonic forces causes tension which pulls the rocks apart*.
- Reverse Faults-occur when forces causes compression which push the rocks together.
