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Geography
Lesson 2
Inside The Earth
A. Layers of the Earth
1. core – hot iron mixed w/ other metals and rock
2. mantle – layer of rock 1800 miles thick
- sometimes melts into liquid (lava)
a) magma – melted rock – comes to surface
through volcanoes.
3 crust – outer surface of the earth – 31-62
3.
31 62 miles thick
a) includes ocean floor and continents
B Plate Tectonics
B.
1. crust consists of large plates of rock floating on liquid below
the surface.
a)) oceans andd continents
ti t sit
it on these
th
plates
l t
2. Pangaea – landmass of continents which were once
joined together – over time they have moved apart.
a) plates move 1 – 4 inches per year – millions of years.
3. When Plates Meet
a) mountains – formed when plates collide.
collide
b) volcanoes – when pressure builds between
two plates.
c) earthquakes – violent sudden movement of plates
d) tsunami – huge wave caused by underwater earthquake
1) faults – cracks in earth crust – violent earthquakes
often happen near these
4 Sh
4.
Shaping
i th
the Landforms
L df
a) weathering – breaking surface rock into boulders, gravel,
sand, and soil.
1) caused by heating, cooling, chemicals, plant growth, etc.
b) erosion – wearing away material
1) water Æ rain, streams, oceans, etc.
2) wind
i d Æ carries
i away loose
l
soil
il
3) glaciers Æ sheets of ices slowly moving leave mountains
and valleys behind
5. Types of Landforms
a) mountains – towers of rock formed by tectonic collision
1) Mt. Everest – 29,035 feet – highest in world
2) elevation – height above sea level
b) plains – low lying stretch of flat land
c) plateau – flat land at higher elevation
d) valley – area of low land w/ mountains on both sides
e) canyon – lowland created by water erosion
1) Grand Canyon – carved by Colorado Riv.
f) isthmus – narrow strip of land connecting two larger areas
g) peninsula – land w/ water on 3 sides
h) island – land completely surrounded by water
6. Under the Water
a) continental shelf – plateau off the coast of each continent
b) trenches – valleys in ocean – thinnest part of earth’s
earth s crust
1) Mariana Trench – 35,840 feet deep
7. Bodies of Water
a) Ocean – 70% of earth’s
earth s surface – includes seas, gulfs, bays
b) strait – narrow body of water between two pieces of land
c) channel – wider body of water separating land
d) lakes – bodies of fresh water
e) rivers – flow from a source at high elevation - empty into
another body of water (mouth)
f) delta – soil and sand build up at mouth of body of water
water.