Sedimentary Petrology 03: Sedimentary rock classification - Part 1

Sedimentary Petrology 03: Sedimentary rock classification - Part 1.

This video lecture series on Sedimentary Petrology (Undergraduate course GY 402) was made by Dr. Douglas W. Haywick from the Department of Earth Sciences at University of South Alabama.

Some of the contents on this page is outside the scope of the lecture.

Sediment motions

Rest (no movement)
Roll
Slide
Saltation ("bouncing")
Suspension
Mass flow (viscous flow)

Sediment gravity flow

Clastic Sedimentary Rocks
Name of Rock	Sediment Type	Texture
Conglomerate	gravel - rounded fragments	coarse - over 2 mm
Breccia	gravel - angular fragments	coarse - over 2 mm
Sandstone	sand	medium - 1/16 to 2mm
Siltstone	mud	fine - 1/256 to 1/16 mm
Shale	mud	very fine - less than 1/256 mm

Chemical Sedimentary Rocks
Name of Rock	Composition	Texture
Crystalline Limestone	Calcite - CaCO₃	coarse to fine crystalline
Fossiliferous Limestone	Calcite - CaCO₃	visible fragments of shells
Chert	Quartz - SiO₂	very fine crystalline
Gypsum	Gypsum - CaSO₃-2H₂O	fine to course crystalline
Rock Salt	Halite - NaCl	fine to course crystalline
Bituinous Coal	Organic Matter	fine

Turbidity current
Fluidized sedimental flow
Grain flow
Debris flow

Sediment support mechanism

Turbulence
Upward intergranular flow
Grain interaction
Matrix strength

Sedimentary rock classification

Sedimentary rock is classified into two groups based on how they form. They are clastic and chemical.

Clastic sedimentary rock

Clastic sedimentary rock is formed as bits of weathered rock become cemented together. Because all kinds of rock are subject to weathering many different minerals can make up this group of rocks. Clays and quartz are the most common.

Clastic sedimentary rock classification

Classification of clastic sedimentary rocks is done according to the size of the sediments that make up the rock.

Chemical sedimentary rock

Chemical sedimentary rocks form from dissolved minerals that are precipitated or separated from water. This happens most frequently when water evaporates leaving the minerals behind.