Transcript Sedimentary Rocks

Sedimentary Rocks
Sedimentary Rocks are formed at or near the
Earth’s surface
No heat and pressure involved
Strata – layers of rock
Stratification – the process in
which sedimentary rocks are
arranged in layers
This is a good example of Stratification
SEDIMENTARY ROCKS
There are 2 ways sedimentary rocks are formed
1.
Clastic are made from sediments glued
together
2.
Non-clastic: not glued together---include
chemical & biochemical/organic
SEDIMENTARY ROCKS MAY CONTAIN FOSSILS.
THE 2 CLASSES OF SEDIMENTARY ROCKS
1. CLASTIC Sedimentary Rocks formed from the processes
of weathering, erosion (transportation), deposition, then
lithification.
2. Lithification is the process of compaction and
cementation of the clasts, or particles from weathering.
http://geologylearn.blogspot.com/2015/11/classes-of-sedimentary-rocks.html
Weathering
The 2 types of weathering include physical (only size
changes) and chemical (a new substance is formed).
Sediments range in size from tiny pieces of clay to sand,
to pebbles, and to stuff as big as boulders
Sediments can be angular to rounded, and well or
poorly sorted
http://geologylearn.blogspot.com/2015/11/classes-of-sedimentary-rocks.html
Here’s How They Form:
•Layers of sediment are deposited at the bottom of oceans
and lakes
•As the layers build one on top of another, the pressure on
the bottom layers COMPACTS the sediments together
•In the empty spaces between sediments, natural glues, like
calcite, CEMENT the sediments together
Demo
of
Sedimentator
Look at the processes
that are occurring in
this animation
Clastic Process
Examples of clastic sedimentary rocks include
CONGLOMERATE
SHALE
BRECCIA
SANDSTONE
Clastic
sedimentary
rocks are
classified by
their grain
size, and
shape of the
grains.
http://geologylearn.blogspot.com/2015/11/classes-of-sedimentary-rocks.html
http://geologylearn.blogspot.com/2015/11/classes-of-sedimentary-rocks.html
Common Clastic Rocks
Breccia – course,
angular clasts >2mm
Conglomerate –
course, rounded
clasts > 2mm
Sandstone – clasts fine to
course, >0.05 mm to <2 mm
(cemented sand), occurs in
many colors. Feels gritty.
http://northern-arizona-uranium-project.com/breccia_pipe_anatomy
https://www.geolsoc.org.uk/ks3/gsl/education/resources/rockcycle/p
age3458.html
Common Clastic Rocks
Shale – made from clay, grains
are small and flat. Breaks into
thin pieces with sharp edges.
Usually gray, brown, reddish
brown or green.
Siltstone – fine grained, clasts
smaller than sandstone <0.05 mm,
occurs in many colors due to
composition or staining from
surrounding minerals. Feels smooth
or powdery
www.geology.com/rocks
2. Non-Clastic contain 2 types:
chemical and biochemical
Sedimentary Rocks made from mineral crystals that formed
from chemical or biochemical deposition.
Here’s How They Form:
•The water in the oceans, lakes, and
underground is often full of dissolved
minerals like halite and calcite.
•Water evaporates leaving the solids
behind: rock salt is formed when salt
is left after evaporation and limestone
is formed when calcite is left behind
Chemical Sedimentary Rocks are also formed in caves
where mineral-rich water drips from the ceiling, creating
stalactites and stalagmites made out of limestone
Limestone
Limestone Cave
Examples of chemical
sedimentary rocks
include limestone and
rock salt
BIOCHEMICAL OR ORGANIC Sedimentary Rocks are
made from remains of once-living plants or animals
(organic matter)
•will be found near areas of lots of biological activity
•this is the sedimentary rock type with the most fossils
Biochemical sedimentary rocks include: coquina, chalk,
coal and limestone
COQUINA
Made from
shells
CHALK
Made from dead
animals
COAL
Made from
dead plants
LIMESTONE
with
fossils in it
In Summation:
1. Sedimentary rocks form 3 ways:
Clastic --compacted & cemented
1. _________
2. _____________
Non-Clastic : Chemically or Biochemically
deposited
strata
2. Sedimentary rocks are found in flat layers or _______
Fossils (remains of plants and animals) are found in
3. _______
Sedimentary Rocks.
Limestone formed both chemically and organically.
4. ____________is
5. Clastic rocks are made of _____________,
sediments examples
are conglomerates, sandstone and shale
6. Chemically formed sedimentary rocks form from
evaporating ocean water, which leaves behind
_____________
evaporates like ___________,
rock salt or from precipitates.
7. Some common sedimentary rocks are:
Shale, limestone, sandstone, siltstone, coal,
chalk, coquina, breccia, conglomerate
sedimentary review/