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Map 2
1. earthquakes and volcanoes rates of change weathering and erosion rocks and sediments
9-12
The formation, Scientific evidence
weathering, implies that some rock
sedimentation, and near the earth's surface
reformation of rock is several billion years
constitute a continuing old. But until the 19th
"rock cycle" in which century, most people
the total amount of believed that the earth
material stays the same was created just a few
as its forms change. thousand years ago.
Earthquakes often occur
along the boundaries
between colliding
plates, and molten rock
from below creates
pressure that is
released by volcanic
eruptions, helping to
build up mountains.
Under the ocean basins,
molten rock may well up
6-8
Sedimentary rock buried Thousands of layers of
deep enough may be sedimentary rock confirm
reformed by pressure and the long history of the
heat, perhaps melting changing surface of the
and recrystallizing into earth and the changing
different kinds of rock. life forms whose remains
These re-formed rock are found in successive
layers may be forced up layers. The youngest
again to become land layers are not always
surface and even found on top, because of
mountains. Subsequently, folding, breaking, and
The interior of the Sediments of sand and
earth is hot. Heat flow smaller particles
and movement of material (sometimes containing
within the earth cause the remains of
earthquakes and volcanic organisms) are gradually
eruptions and create buried and are cemented
mountains and ocean together by dissolved
basins. minerals to form solid
rock again.
The earth's surface is
The earth first formed shaped in part by the
in a molten state and motion of water and wind
then the surface cooled over very long times,
into solid rock. which act to level
mountain ranges.
Rivers and glacial ice
carry off soil and break
down rock, eventually
depositing the material
in sediments or carrying
it in solution to the
sea.
Some changes in the
earth's surface are There are a variety of
abrupt (such as different land forms on
earthquakes and volcanic the earth's surface
eruptions) while other (such as coastlines,
changes happen very rivers, mountains,
slowly (such as uplift deltas, and canyons).
and wearing down of
mountains).
Vibrations in materials
set up wavelike
disturbances that spread
away from the source.
Sound and earthquake
waves are examples.
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Rock is composed of
Waves, wind, water, and different combinations
ice shape and reshape of minerals. Smaller
How fast things move the earth's land surface Things on or near the rocks come from the
differs greatly. Some by eroding rock and soil earth are pulled toward breakage and weathering
things are so slow that in some areas and it by the earth's of bedrock and larger
their journey takes a depositing them in other gravity. rocks. Soil is made
long time. areas, sometimes in partly from weathered
seasonal layers. rock, partly from plant
remains-and also
contains many living
Things change in steady,
repetitive, or irregular
ways-or sometimes in
more than one way at the
same time. Often the
best way to tell which
kinds of change are
happening is to make a
table or graph of
measurments.
K-2
Chunks of rocks come in
Some changes are so slow many sizes and shapes,
or so fast that they are from boulders to grains
hard to see. of sand and even
smaller.
Change is something that
happens to many things.