Transcript 3 Types of Sedimentary Rocks

Formed
from
sediments.
Sediments
- rock
fragments, mineral
grains, or animal &
plant remains.
 These
sediments are moved by wind,
water, ice or gravity.
 Sedimentary rocks represent 7% of the
Earth’s crust, but they cover 70% of
the Earth’s surface.
 Sedimentary
rocks.
rocks are fossil-carrying
What turns sediments into solid rock?
Lithification
– process of
turning loose sediments
into solid sedimentary
rocks.
What turns sediments into solid rock?
 Water
or wind breaks down and
deposits sediment (erosion & deposition)
Compaction
 As
sediment builds up, the weight of
overlying material compresses
deeper sediments.
 The
deeper a sediment is buried, the
more it is compacted and the firmer
it becomes.
 Cementation
- Dissolved minerals flow
between the particles and cement them
together.
How can sedimentary layers help us
understand the age of fossils?
As sedimentary
rocks are
deposited, they
form horizontal
layers.
 Scientists know
that the layers on
top (and the fossils
in the top layer) are
YOUNGER than the
fossils in lower
layers.

3 Types of Sedimentary Rocks
1. Detrial
2. Organic
3. Chemical
3 Types of Sedimentary
Rocks:
 Detrial
(also called clastic)—made of
broken pieces of other rocks.
Examples
Shale, Sandstone,
Conglomerate, and Breccia
3 Types of Sedimentary
Rocks:
Organic—remains of plants and animals are
deposited in thick layers.

Ex. Fossil rich limestone is made from the
shells of ocean animals; used to make
chalk
3 Types of Sedimentary
Rocks:
 Chemical—minerals
dissolved in
lakes, seas, or underground water.
Mineral crystals are made as the shallow water that has
flooded the bottom of Death Valley evaporates.
Click on image for full size (66K JPG)
Courtesy of Martin Miller, University of Oregon
Examples
 Limestone
made when
calcite
mineral
precipitates
from sea
water .

Rock Salt—
made from
evaporation
of sea
waters.