JOURNAL #43
Explain
the difference between
coarse-grained and fine-grained
igneous rock.
Describe the process of
compaction and cementation.
(Refer to page 135 in your
textbook)
TODAY, WE WILL DESCRIBE HOW
SEDIMENTARY ROCKS FORM.
FORMATION OF SEDIMENTARY ROCKS
 Loose
fragments of rock, minerals and
organic material are called sediment.
 After sediments form, they are
transported by wind, water or ice to a
new location.
 As sediments moves, it is physically and
chemically changed as is deposited.
FORMATION OF SEDIMENTARY ROCKS
 Sediment
becomes sedimentary rock in 2
ways:
 Compaction
Sediment is squeezed and in which the
size of the pores space between sediment
grains is reduced by the weight and
pressure of upper layers.
 Cementation
Sediments are glued together by
minerals that are deposited by water.
SEDIMENTARY ROCK CHANT
BREAK
MOVE
DROP
BREAK
MOVE
DROP
All of these processes happen to a rock
Weathering breaks it
Erosion takes it
And when the motion stops
Gravity drops
Wind and water move it around
Gravity pulls it down
BREAK
MOVE
DROP
BREAK
MOVE
DROP
All of these processes happen to a rock
3 MAIN CLASSES OF SEDIMENTARY ROCK
1.
Chemical sedimentary rock


2.
Forms from minerals that were once dissolved in
water.
Water evaporates out and leaves behind a rock
Organic Sedimentary Rock
Forms from the remains of living things
 Examples: shellschalk

3.
Clastic Sedimentary Rock
Forms when fragments of pre-existing rocks are
compacted and cemented together.
 Examples: sandstone

CHARACTERISTICS OF CLASTIC
SEDIMENTS
 Sorting-
tendency for rocks to arrange by
size.
Well-sorted sediment have grains of the same size.
 Poor-sorted sediment has grains of different sizes.

 Angularity

As sediment is transported, collisions occur
between the rocks and break. They are angular
and uneven.
SEDIMENTARY ROCK FEATURES
Deposition environment
 Setting in which sediment is deposited
 Examples: beaches, oceans, rivers
 Stratification
 Layering of sedimentary rock

 Cross-Beds
and Graded Bedding
 Ripple Marks
 Mud Cracks

Muddy deposits dry and shrink
 Fossils

Remains of plants and animals
 Concretions-

lumps of rock that come from a different rock
REVIEW
 The
process in which sediment is squeezed
and the pore space is reduced by weight and
pressure of the upper layers is called___
A. Compaction
B. Cementation
ANSWER: A
REVIEW
What
is cementation?
Answer: sediments are glued by
minerals that are deposited by water
REVIEW
 Which
of the following is not one of the classes
of sedimentary rock
A.
B.
C.
D.
Physical
Chemical
Organic
Clastic
ANSWER: A
REVIEW
 What
are the 7 features that you can used to
identify the depositional environment in
which sedimentary rocks formed?
Answer: Stratification, cross-beds, graded bedding,
ripple marks, mud cracks, fossils, concretions