Transcript Earth`s Interior

Earth’s Interior
Earth’s Interior
•
Earth’s interior is made up of 5 zones:
1. Crust: ~25 km in depth. It is like the skin of
an apple. The crust varies in thickness;
thinner oceanic and thicker continental.
2. Mantle: 2900 km in depth. It is the largest
of Earth’s zones. It is solid rock, but parts
of it flow slowly upward or downward,
depending on whether it is hotter or
colder than the mantle next to it.
• Lithosphere: ~100 km in depth. It includes
the crust and the uppermost part of the
mantle. It is relatively rigid.
• Asthenosphere: ~100 km in depth. The
uppermost mantle underneath the
lithosphere. It is soft and flows more
readily than the mantle. It provides a layer
over which the lithosphere moves.
• Core: 3470 km in depth. It is the center of
the Earth. There is a solid inner core and a
liquid outer core.
Plate Tectonics
Theory of Plate Tectonics
• Tectonic forces: forces generated
inside the Earth cause de-formation
of rock as well as vertical (↕) and
horizontal (↔) movement of portions
of the Earth’s crust; most are
mechanical forces.
• Plate tectonics is a unifying theory
that accounts for seemingly unrelated
geologic events.
–Explains where and why we get
earthquakes, volcanoes, mountain
belts, deep ocean trenches, and
mid-oceanic ridges.
• Plate tectonics was seriously
proposed as a hypothesis in the early
1960s, though it was based on the
theory of continental drift.
–Continental drift stated that the
continents drifted over the crust.
Boundaries
• Plate tectonics regards the lithosphere as
broken into plates that are in motion;
moving relative to one another, sliding on
the underlying asthenosphere.
• There are three types of plate movement:
– Divergent boundaries
– Convergent boundaries
– Transform boundaries
Divergent Boundary
• These boundaries exist where plates
move apart.
• Most are under the ocean and create giant
mountain ranges, called mid-oceanic
ridges.
• New oceanic crust is continuously being
created (sea-floor spreading).
• The rate of motion is usually 1-18 cm/y.
Convergent Boundary
• The plates are moving toward each other.
• Oceanic crust is forced underneath the
continental crust; this region is called a
subduction zone.
• Old oceanic crust is destroyed, producing
magma and causing earthquakes.
• On land, mountains are created from
convergent boundaries.
• Under water, trenches are created.
• There are 3 types:
– Continental plate with continental plate
– Continental plate with oceanic plate
– Oceanic plate with oceanic plate
Transform Boundary
• Occurs when two plates slide past each
other; often causing earthquakes.
• It is also known as a Transform Fault
Boundary because it creates faults.
• No new crust is created, or old crust
destroyed.