Download Earth Interior and Plate tectonics

Earth Interior and Plate
tectonics
• Crust- the thin and solid outermost layer of
Earth above the mantle
• The crust beneath the ocean is called oceanic
crust and has an average thickness of 58km(3.1-4.9miles)
• Continental crust is less dense and thicker,
with average thickness of about 20-40 km (1225 miles)
• Mantle- the layer of rock between’s Earth’s
crust and core ( is denser than the crust)
• Mantle almost 2900km(1800 miles) thick,
makes up 80% of Earth volume
• Because humans have never drilled all the way
to the mantle, we don’t know for sure what is
like. Geologic events, like earthquake and
volcanoes, provided evidence of the mantle’s
consistency, the outermost part is rigid like the
crust, and deeper is soft and easily deformed,
like a piece of gum.
• Core- the center part of Earth, mainly
composed of iron and nickel, has two layers
• The inner core -which is solid metal,
surrounded by the liquid metal -outer core .
• Earth’s interior gets warmer with depth
• The temperature in the cave is cool, because the
air and the rocks beneath Earth's surface are
shield from the warming effects of the sun
• The temperature in gold mines in Africa reach
depths of up to 3 km (2 mi) and their
temperature 50oC(120oF)
• Radioactive elements contribute to Earth's high
internal temperature. Earth's interior contains
radioactive isotopes (uranium, thorium and
potassium- are quite rare), their nuclei break up,
releasing energy as they become more stable.
• In 1915, German scientist Alfred Wegner noticed that
the eastern cost of _____ and the western cost of
______, appeared to fit together
• He pieced all the continents together to form a
supercontinent called Pangaea (approximately 200
million years ago
• The evidence of “continental drift”, new technology
provided images of “bands” of rock on the ocean
floor with alternating magnetic polarities, like the
bands in the figure.
• These bans differ in the alignment of the magnetic
minerals in the rocks they contain. The rocks are
younger near the canter of the ridge.
• Lithosphere – the solid, outer layer of Earth,
that consists of the crust and the rigid upper
mantle
• Lithosphere is approximately 100km (60mi), and
is made up of about 8 large pieces (and several
small) called plate tectonics
• Plate tectonics- the theory that explains how
the outer parts of Earth change through time,
and explains the relationship between
-continental drift ,
-sea-floor spreading,
-seismic activity
-and volcanic activity
• North American Plate - North America, western North
Atlantic and Greenland
• South American Plate - South America and western South
Atlantic
• Antarctic Plate - Antarctica and the "Southern Ocean"
• Eurasian Plate - eastern North Atlantic, Europe and Asia
except for India
• African Plate - Africa, eastern South Atlantic and western
Indian Ocean
• Indian-Australian Plate - India, Australia, New Zealand and
most of Indian Ocean
• Nazca Plate - eastern Pacific Ocean adjacent to South
America
• Pacific Plate - most of the Pacific Ocean (and the southern
coast of California)
• Tectonic plates move at speeds ranging
from 1-16 cm (0.4-6.3in) per year.
• Some plates move toward each other,
some moves away from each other, and
others move alongside each other.
• The theory of plate tectonics help
scientists study and sometimes predict
volcanic eruptions and has provided
information on earthquakes.
• Mid-oceanic ridges result from divergent
boundaries
• A divergent boundary occurs where
two plates move apart, creating gap
between them
• When this happens, hot rock rises from
asthenosphere and cools, forming
lithospheric rock
• The drop in pressure causes the rising
asthenosphere to partially melt, forming
magma, which separates to form new
oceanic crust
• Magma- liquid rock produced under
Earth's surface
• Mid- oceanic ridges are mountains
ranges at divergent boundaries in oceanic
crust
• As the plates move apart, magma rises
from between the diverging plates and fills
the gap.
• The new oceanic crust forms a large
valley, called rift valley, surrounded by
high mountains
• Oceanic plates dive beneath
continental plates at
convergent boundaries
• New lithosphere is formed,
and older lithosphere is
destroyed at convergent
boundaries
• Subduction – the process
by which one lithospheric
plate moves beneath
another as a result of
tectonic forces
• Subduction of oceanic crust
generates volcanoes
• Colliding tectonic plates
create mountains. The
Himalayas, formed during the
collision between the India
and the Eurasia continental
plates, Mount Everest is part
of this range, his peak is 8
850m or 29 034 ft above sea
level
• Plate movement ca cause
breaks in lithosphere
• Fault- a crack in Earth
created when rocks on
either side of break move
• When rock moves horizontally at faults
along plate boundaries, is called a
transform fault boundary, and is one cause
of earthquakes
• San Andreas fault runs from mexico
through California and out sea north of
San Francisco