Name: _____________________________
Sedimentary Rocks
How SEDIMENTARY Rock Is Formed
The earth's surface is constantly being
eroded. This means that rocks are broken
up into smaller pieces by weathering agents
such as wind, water, and ice. These small
pieces of rock turn into pebbles, gravel,
sand, and clay. They tumble down rivers
and streams. These pieces settle in a new
place and begin to pile up and the
sediments form flat layers. Over a long
period of time, the pieces become pressed
together and form solid rock called
sedimentary rock. Most sedimentary rocks
form under water. Most of the earth has
been covered by water some time in the
past. 70% of the earth is covered by water
now. So sedimentary rocks are common all
over the world. Sedimentary rocks are
often rich in fossils.
Sediments can harden into sedimentary
rock in two ways.
pressure-As layer after layer of
sediments are deposited, the lower
layers are pressed together tightly
under the weight of the layers above.
cementing-Some sediments are glued
together by minerals dissolved in
water
Sedimentary Rock forms from particles, called sediment, that are worn off other rocks.
The particles are sand, silt, and clay. Sand has the largest particles while clay has the
smallest. If there are a lot of pebbles mixed with the sand, it is called gravel. The
sediment gets turned into rock by being buried and compacted by pressure from the
weight above it. Another way it becomes rock is from being cemented together by
material that has been dissolved in water. Often, both cementing and compaction take
place together. For thousands, even millions of years, little pieces of our
earth have been eroded--broken down and worn away by wind and water.
These little bits of our earth are washed downstream where they settle to
the bottom of the rivers, lakes, and oceans. Layer after layer of eroded
earth is deposited on top of each. These layers are pressed down more and
more through time, until the bottom layers slowly turn into rock.
http://www.fi.edu/fellows/fellow1/oct98/create/sediment.ht
m
Examples of Sedimentary Rocks
SHALE
.
SANDSTONE
Sandstone is a clastic sedimentary rock made up mainly of sand-size (1/16 to 2
millimeter diameter) weathering debris. Environments where large amounts of
sand can accumulate include beaches, deserts, flood plains and deltas.
COAL
Coal is an organic sedimentary rock that forms from the accumulation and
preservation of plant materials, usually in a swamp environment. Coal is a
combustible rock and along with oil and natural gas it is one of the three most
important fossil fuels. Coal has a wide range of uses; the most important use is
for the generation of electricity.
http://geology.com/rocks/sedimentary-rocks.shtml#conglomerate
CONGLOMERAT
E
Conglomerate is a clastic sedimentary rock that contains large (greater than two
millimeters in diameter) rounded clasts. The space between the clasts is generally
filled with smaller particles and/or a chemical cement that binds the rock
together.
LIMESTONE
Limestone is a rock that is composed primarily of calcium carbonate. It can form
organically from the accumulation of shell, coral, algal and fecal debris. It can also
form chemically from the precipitation of calcium carbonate from lake or ocean
water. Limestone is used in many ways. Some of the most common are:
production of cement, crushed stone and acid neutralization.
http://www.fi.edu/fellows/fellow1/oct98/create/metamorph.htm
SEDIMENTARY Rocks Notes
What are they?
________________________________________________________________________
____________
The ways sedimentary rocks are formed:
1) __________________________
2)__________________________
3)
The types of sediment these rocks are made from are:
Fossils are most commonly found in
a. igneous rocks
b. sedimentary rocks
c. metamorphic rocks
d. all of the above
Exploring Sedimentary Rocks
List 5 sedimentary rocks and describe each.
Rock Name
1)
2)
3)
4)
5)
Description- What do you notice? Look at
its crystal size, texture, color, etc.
Do you think the rock was cooled
above or below the Earth’s
surface (intrusive or extrusive)?
Why?