Unit 4 - Lithosphere

• Types of plate boundaries - Divergent, Convergent, Transform
• Divergent Boundaries - 2 plates moving away
• Convergent Boundaries - 2 plates moving together
• Transform Boundaries - 2 plates grind ( slide ) past eachoter
• Divergent Boundaries - As the plates move apart, magma rises, fills in the space between the plates, cools and hardens. Ridges are mainly found on the ocean floor while rifts are found on land.
• Rift - splitting of continental crust
• With rifts, eventually a rift valley will form, followed by a sea because water fills inside of the rift valley.
• Continental/Oceanic Convergent - Oceanic crust is forced under continental crust, as the oceanic crust subducts into the mantle it melts. This forms volcanoes on land and trenches offshore.
• Continental/Continental Convergent - Edges collide, crumple, and uplift into folded mountain ranges. These mountains are not volcanic.
• Oceanic/Oceanic - Older oceanic crust subducts, this forms trenches and volcanic Island arcs.
• Ridge Push - occurs when the weight of the ridge pushed the rest of the tectonic plate away from the ridge, often towards a subduction zone.
• Transform Boundaries - creates earthquakes and strike/slip faults.
• Convection Currents - causes the plates to move, a cycle of hot material rising and cooled material sinking
• Oceanic Crust - 3 to 4 miles thin, very dense
• Continental Crust - 20 to 30 miles thin, not that dense
• Evidence for Continental Drift : Puzzle Pieces, Fossils, Rock types and Structures, Ancient Climates
• "Puzzle Pieces" - Continents look like they could be part of a giant puzzle, Pangaea
• Distribution of Fossils - Plant and animal fossils found on the coastlines of different continents that look like they connect
• Rock Types and Structures - several mountain ranges end at one continents edge and reappear at the edge of another continent, this implies that they were once connected
• Ancient Climates - Glacial sheets have been found in Africa, South America, and other areas, this shows that those areas once had ice. There was also coal in Antarctica, meaning that there had to be a forest, meaning it was warm at some point.
• Crust - the thin, rocky outer layer of the Earth
• Mantle - a solid, rocky shell that extends to a depth of 2890 km
• Regions of NC : Mountains, Piedmont, Inner Coastal Plain, Fall Line, Tidewater ( Outer Coastal Plain )
• Mountains - The African continental plate and the North African plate collided. The collision and plate break up caused the mountains. This happened 450 million years ago. A string of mountains. It was a source of mineral resources and provides Christmas trees.
• Piedmont - African and North America were moving close together. Parts of the seafloor and a group of volcanic islands also collided with North America. This happened 400 million years ago. It is a broad plateau with low mountains and gently rolling hills. Fertile agriculture region.
• Inner Coastal Plain - Africa and America began to split, the Atlantic ocean formed. Rivers carried sediment from the mountains which helped form the coastal plain. This happened 200 million years ago. It is flat, poorly drained, swampy and beachy. There is good farmland here.
• Tidewater ( Outer Coastal Plain ) - The sea level rose after the last ice age thousands of years ago. Here there are swamps, beaches and estuaries. The tidewater protects the mainland.
• Fall Line - A line that forms the border between the coastal plain and the piedmont.
• Evidence of Plate Tectonics - Paleomagnitism, Earthquake patterns, Ocean Drilling ( age of ocean floor ), Hot Spots.
• Paleomagnetism - the permanent magnetic field of a rock that shoes the direction of the magnetic field at the time of the rocks formation.
• When hot minerals in newly formed rocks align themselves with the Earth's magnetic poles
• As the Earth's magnetic poles change, so do the direction of the rock's magnetic poles
• Rocks formed millions of years ago show the location of Earth's magnetic poles at the time of their formation
• Earthquake patterns ( convergent boundaries ) - There is a link between deep-focus earthquakes and ocean trenches. Shallow earthquakes occur near or at the trench. Deep earthquakes occur toward the mainland.
• Ocean Drilling ( Age of Ocean Floor ) - Older rocks are found closest to the shoreline and youngest are found near the ridge. This proves that the ridge is producing new oceanic crust while the old crust is being pushed toward the shoreline.
• Hot Spots - Rising Magma from the mantle that produces volcanoes. As plates move, new volcanoes are formed. The hot spot stays still and the plates move.
• Earthquake - a vibration of the Earth produced by a rapid release of energy, they often occur along faults
• Faults - breaks in the Earth's crust and mantle
• Focus - point WITHIN the Earth where the earthquake starts
• Epicenter - point on the Earth's SURFACE directly above the focus