1. Assignment# 10 Sedimentary Rocks
How do they form?

2. SEDIMENTARY ROCKS SEDIMENTARY ROCKS WILL CONTAIN FOSSILS.
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 WILL CONTAIN FOSSILS.

3. Oldest rocks are on the bottom….youngest on top
SEDIMENTARY ROCKS FORM IN LAYERS
CALLED STRATA
Oldest rocks are on the bottom….youngest on top

4. This is a good example of Stratification

5. THE 2 CLASSES OF SEDIMENTARY ROCKS
1. CLASTIC Sedimentary Rocks are made from sediments that come from pre-existing rocks that have been weathered (breaking down into smaller pieces) and eroded (transported away) then glued together.
The 2 types of weathering include physical (only size changes) and chemical (a new substance is formed).

6. Sediments range in size from tiny pieces of clay to sand, to pebbles, and to stuff as big as boulders
Clastic rocks form in a process called lithificaton which means compaction and cementation are occurring

7. Layers of sediment are deposited at the bottom of oceans and lakes
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

8. Look at the processes that are occurring in this animation

9. Clastic Process

10. Examples of clastic sedimentary rocks include
CONGLOMERATE
BRECCIA
SHALE
SANDSTONE

11. Non-Clastic contain 2 types: chemical and biochemical
CHEMICAL Sedimentary Rocks are made from mineral crystals that formed from chemicals dissolved in water.
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

12. 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

13. will be found near areas of lots of biological activity
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
CHALK
Made from dead animals
COAL
Made from dead plants
COQUINA
Made from
shells
LIMESTONE
with
fossils in it