Note taking pg 198-211

• 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.