CHAPTER 7 SUMMARY
Continental Drift- Continents have moved slowly to their current locations/
Pangea- means all land. At one time, it was theorized that the continents were all grouped together in one big land mass.
Glossopteris- is a fossil that supports the hypothesis of the continental drift.
Seafloor Spreading- is a famous theory Harry Hess proposed that hot, less dense material below Earth’s crust rises toward the surface at the mid-ocean ridges.
Magnetometer- is a device that detects magnetic fields.
Plate tectonics- theory that earth’s crust and upper mantle are broken into plates that float and move around on a plastic-like layer of the mantle.
Plates- a large section of earth’s oceanic or continental crust and rigid upper mantle that moves around on the asthenosphere.
Lithosphere- rigid layer of earth about 100 km thick, made of the crust and a part of the upper mantel.
Asthenosphere: the plastic-like layer below the lithosphere.
Convection Current: the entire cycle of heating, rising, cooling, and sinking.
Earth’s magnetic field has a north and south pole.
When plates move, they can interact in several ways. They move towards each other and converge, which means to collide.
Plates moving apart are called a divergent boundary.
Where plates slide past each other is called a transformed boundary.
Heating, rising, cooling, and sinking is called convection current.
Faults when rocks break and move along surfaces rift valleys and mid-ocean ridges can form where Earth’s crust separates
Mountains and volcanoes:
the type of faulting that produces them is generally reverse faulting.
Strike-slip faults transformed boundaries, two plates slide past one another without converging or diverging.
Harry Hess- proposed sea floor spreading
As Earth’s plates move apart at boundaries, they collide at others. Ocean basins, mountains, and volcanoes form.
Youngest rocks at ocean located at mid ocean ridges
Plate movements seen at RIFT VALLEYS and PLATE BOUNDARIES
FOSSILS and ROCKS on different continents
Support CONTINENTAL DRIFT
CONTINENTAL DRIFT OCCURS because of SEA FLOOR SPREADING
CONVECTION CURRENT- Rising, heating, cooling, and sinking of a fluid is called convection current. Happens with magma and that is why the PLATES float
CONTINENTAL DRIFT- Continents drifted to their current locations
OCEAN ROCKS are younger than CONTINENTAL ROCKS (form due to SEA FLOOR SPREADING)
Earth’s magnetic poles have shifted many times! We can tell this due to elements of iron in rock on the sea floor.
Make sure to review!
SEA FLOOR SPREADING