Download Forces Shaping Earth

Forces Shaping Earth
6th
Notes
Mrs. Seay
Grade Science
 Geologists
use earthquakes and
surface rocks to indirectly observe
Earth’s interior
 1.
Seismic waves change speed and
direction depending on the density
and material they travel through.
 2.
Forces bring rocks formed deep
within Earth to the surface.
 3.
Evidence suggests that Earth is
formed of different materials in
layers.
 B.
Earth has four layers.
 Inner
core—dense iron core; very
hot and dense.
 Outer
core—molten metal above the
inner core
 Solid
layer that flows slowly like
putty is the mantle.
 Outermost
layer is the crust.
 C.
Earth’s structure—theories based
on physical properties of density,
temperature, and pressure that
change with depth.
 Earth’s
moving plates are sections of
the lithosphere, the rigid upper part
of the mantle and crust.
 Plate
boundaries are edges where
plates meet.
 Tension
can pull plates apart,
resulting in new lithosphere forming
in the gaps.
 Colliding
plates could cause
mountains to form as rock crumbles
and folds.
 Subduction
occurs when a denser
plate sinks underneath a less dense
plate.
 Shearing
causes faults and
earthquakes as two plates slide past
each other.
 Plate
movement theory—convection
in the mantle circulates material and
moves plates.
 Ridge-push
at mid ocean ridges
causes plates to slide down the
slope.
 Slab-pull
happens as plates move
away from mid-ocean ridges and
become denser.
 Mountains
form in different ways.
 Fault-block
mountains form from
huge tilted blocks of rock separated
from surrounding rock by large
faults.
 Folded
mountains form by
compression forces folding rock
layers.
 Upwarped
mountains—forces push
up Earth’s crust and allow the
sedimentary rock to erode, leaving
igneous or metamorphic rock.
 Over
time, layers of lava can form a
cone-shaped volcanic mountain.
 Hot
spots formed by plumes of
magma in the mantle can cause
underwater volcanic mountains.
 Isostacy
principle in dicates Earth’s
crust and lithosphere float on the
upper mantle.
 Earth’s
crust is thicker under
mountains.
 When
mountains erode, the crust
rises because the weight has been
removed.