Sedimentary Geology

Sedimentary Origins/Classifications

•

Sedimentary rock forms as a result of three general situations
called “origins”

1.

Clastic

2.

Biochemical

3.

Chemical

Clastic Sedimentary Rock

• Rock that forms as a result of

fragments or rock material
either compacted or cemented

• Common Clastics:
Shale = formed by compaction
Sandstone = formed by

compaction + cementation

Conglomerate = formed by

cementation

​Siltstone and Mudstone are common
in the badlands here

Multiple Choice

Which of the following clastic sedimentary rocks is made of poorly sorted clasts?

• conglomerate

• sandstone

• shale

• limestone

Multiple Choice

Which of the following types of clastic sedimentary rock would have microscopically small, flat, grains?

• conglomerate

• sandstone

• shale

• limestone

Chemical Sedimentary Rock

• Rock that forms as a result

of material coming out of
solution (precipitate) or
from evaporation of water
leaving minerals behind
(evaporite)

• Limestone = common

precipitate rock

• Rock salt = common

evaporite

Dropdown

​

Select answer

sedimentary rocks form when water saturated with ions ​

Select answer

minerals to the bottom of a water column or when water ​

Select answer

and leaves behind minerals.

Multiple Choice

Precipitated calcium carbonate creates the world's most common chemical sedimentary rock, ______

• shale

• limestone

• chert

• gypsum

​Chert - precipitated silica

​Flint - variation of chert

Biochemical Sedimentary Rock

• Rock that forms as a direct

result of organic (living things)
deposition and deformation.

• Examples:
Coal
Organic limestone
Any fossil or fossil imprinted

stone

​Chalk = precipitated calcium carbonate

​Coquina = poorly cemented sea shells

​Oolitic Limestone = shells rounded by wave action

Dropdown

Common biochemical sedimentary rocks include ​

Select answer

, a carbon rich rock used for fuel, ​

Select answer

which is a poorly cemented jumble of sea shells, and ​

Select answer

which is very fine ground up sea shells that settle to the bottom of the sea and cement together.