Unit 4 Day 5
Sedimentary Rocks
VA SOL5. sedimentary (clastic and chemical) rocks; and
Objective
2. Classify sedimentary rocks by texture and composition.
– sandstone, conglomerate, and shale;
– limestone and rock salt.
Sedimentary Rocks
The second classification of rocks includes many of the common types seen on the Earth’s surface. The native rocks found here on the of Virginia are mostly of the sedimentary variety
Sediments are pieces of solid material that have been on the surface by wind, water, ice, gravity or chemical precipitation
Sediments are and to new locations by four main agents: Wind, moving water, gravity, and glaciers
occurs when sediment transport ceases and they are laid down on the ground or sink to the bottom of water
Sedimentary deposits are then in layers called sedimentary basins from to .
These basins can be as much as km thick
Classification of clastic sediments
The sediments that form rocks can be classified according to the .
> 2mm – Gravel
0.062mm - 2mm – Sand
0.0039mm- 0.062mm – Silt
< .0039mm - Clay
Lithification
occurs as the temperature and pressure increases in the buried sediment and the physical and chemical processes transform the sediment into
occurs when mineral growth cements sediment grains together into solid rock
______- the squeezing together of rock fragments from pressure
Types of Sedimentary rocks
The classification of sedimentary rocks is based on how theywere . There are main groups of sedimentary rocks
1. Clastic
sedimentary rocks are formed from the lithification of abundant deposits of found on the Earth’s surface
They can further be classified according to their .
and breccia are examples
Medium-grained clastics consist of -sized particles
Sandstone is a medium-grained clastic rock
Fine-grained clastics are made of and sized particles
2. Chemical
sedimentary rocks form through processes such as when bodies of water become oversaturated with solids.
Crystal grains will out of the solution and settle to the bottom to form layers of chemical sedimentary called .
Types of Sedimentary rocks
is formed this way and the main source of the table salt we use every day
sedimentary rocks are formed from the remains of .
These rocks form in the oceans and as the organisms die their shells settle to the bottom form thick layers of sediment over geologic time.
Eventually these layers of sediment can and become solid rock
is our most common organic sedimentary rock
forms when the remains of material accumulate in swamps and coastal areas. These layers are buried and compressed over millions of years and become lithified.