Geography Unit 1 Geology
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Longitude and Time
- Earth completes a rotation in 24 hours. There are 360 degrees of longitude around Earth, so Earth spins 15 degrees/hour.
- Every 15 degrees west, you are behind one hour.
Political Time Zone
Some time zones are extended to match their political boundaries. Newfoundland is also an exception. It is half an hour ahead of Atlantic time because the island sits farther east than the other provinces in the Atlantic area
- Alfred Wegener theorized that the continents were once together and some how drifted to their current positions.
- The fossils match around join and the geology is similar
Earth's Structure (Crust)
- 40-70 km thick
- cooled magma and lava (igneous) rock.
- It includes continental crust (thicker, mostly granite) and oceanic crust (thinner, basalt)
Earth's Structure (Mantle)
- 70 percent Earth's volume
- Near the melting point of rocks
- Circulates like wet cement (convection currents)
Earth's Structure (Outer Core)
super heated liquid magma (5000 degrees Celsius), slowly churning iron and nickle
Earth's Structure (Inner Core)
Size of the moon. Solid, mostly iron and nickle. Approx 4000 degrees Celsius
How do plates move?
- The magma near the core expands and rises due to the heat. As the magma spreads out, the plates are dragged along and they move away from each other.
- This is the process of sea floor spreading.
- When the magma sinks, the plates are dragged towards each other. This is the process of subduction.
- The continued rising and sinking of the magma set up continuous convection currents in the mantle
Plates that border North America
- Juan de Fuca
- Eurasian Plate
Earliest continents made of granite formed 3 and a half billion years ago in Earth's crust
Form trenches. Both plates go into subduction zones
Oceanic Sinks under Continental and form mountains when Continental plate is lifted up
Both buckle up due to both plates being too light to subduct to the other
- The world's last super continent is known as Pangaea. It began breaking around 250 million years ago.
- South America split off from Africa. NA split from Europe. Australia split from Antarctica
- Plates are moving apart
- Rifting occurs when continental crust split apart.
- Sea floor spreading is when oceanic crust split apart.
- Convection currents come UP from the core.
- Iceland is on the mid-Atlantic ridge and above an additional mantle plume.
- Plates come together
- Convection currents cooling and going back towards core
- Crust can buckle and form mountains
- One plate sliding beneath less dense plate (lighter plate)
- Melting plate puts pressure in mantle volcanoes form above crust.
Plates are moving adjacent to each other. Earth quakes occur when the the plate movement happens
How are Glaciers made
When it is cold enough, snow will fall year round and won't melt in the summer. After a while, the pressure from the snowfall will crush the snowflakes and squeeze them into ice. The in between step is called fern.
- Located in mountains
- Gravity of the slope causes the glacier to move
- Create valleys, cliff faces, and horns
- Deposit drumlins
- Located on the northern ice caps
- Move through their own weight
- Deposit eskers (ridges)
material picked up and carried by glaciers. Everything from sand to giant boulders
- Ridges left of till either at the front or sides of glaciers as it retreats.
- Terminal moraines occur at the front of the glacier and show how far it advanced
Egg shaped hills that usually occur in clusters. They are used for farming due to soil deposits and also mined for gravel.
- A large boulder that is carried by the ice to a spot where it is dropped
- They are easily spotted since they are so different from the rocks around them
A long curvy ridge of sand and gravel deposited by flowing water under a glacier or ice sheet.
Magma and Lava cools to become igneous rock. Through erosion is can become sedimentary rock or can be crushed with heat/pressure to become metamorphic rock. Sedimentary rock can erode and become another sedimentary rock
Canada formation Step 1
Craton forms from volcanoes and is igneous rock. Can be crushed to form igneous rock
Sheild erodes and the layers are carried into surrounding seas. Layers are compressed into sedimentary rock
N.A. collides with Europe. Sedimentary rock layers are uplifted and folded. Erosion of sediments deposit into surrounding seas.
- NA and Pacific collide so West coast is uplifted
- Subduction creates the Coastal Mountains
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