Lecture 8

All the rivers run to the sea, yet the sea is not full: unto the place from whence the rivers come, thither they return again.

- Ecclesiastes 1:7

Sedimentary Rocks

Webpage for course (daytime)

Webpage for course (nighttime)

Three types of rocks:

- Igneous-Sedimentary- Metamorphic

Sedimentary rocks are important because

Form and are common at earth’s surface

Preserve the history of Life (contain fossils)

Sedimentary rocks are important because

Form and are common at earth’s surface

Preserve the history of Life (contain fossils)

Show past environments, climates

Provide a geologic record of past history

Major sources of energy – oil, gas, coal

General History of a Sedimentary Rock

WEATHERING

TRANSPORTATION

DECOMPOSITION

DEPOSITION

LITHIFICATION

Mechanisms of Transportation and Deposition

Water - streams, rivers, etc.,

freshwater and marine

Wind

Gravity – downslope movement

Ice – glaciers

Some sedimentary rocks form of atoms dissolved in water and precipitated elsewhere

Classification of sedimentary rocks

Clastic (Detrital in your book)

Nonclastic

Nonclastic

Example, coal

Nonclastic

Another example, rock salt

Clastic

Classification depends on grain size

Size (mm) particle name

>256

64-256

4-64

2-4

.0625-2

.0039-.0625

<0.0039

Clastic

Classification depends on grain size

Size (mm) particle name rock name

>256 boulder

64-256 cobble

4-64 pebble

2-4 granule

.0625-2 sand

.0039-.0625 silt

<0.0039 clay

Clastic

Classification depends on grain size

Size (mm) particle name rock name

>256 boulder

64-256 cobble

4-64 pebble

2-4 granule

.0625-2 sand sandstone

.0039-.0625 silt

<0.0039 clay

Clastic

Classification depends on grain size

Size (mm) particle name rock name

>256 boulder

64-256 cobble conglomerate

4-64 pebble or breccia

2-4 granule

.0625-2 sand sandstone

.0039-.0625 silt siltstone

<0.0039 clay shale

Why the distinction conglomerate and breccia?

Conglomerate means slow, breccia means sudden

Nonclastic

Chemical Biogenic

Coal

Coquina

Chalk

Diatomite

Diatoms

Nonclastic

Chemical

Rock Salt

Chert

Limestone

Dolomite

Biogenic

Coal

Coquina

Chalk

Diatomite

Coal as Energy