Sedimentary Rocks are formed at or near the Earth’s surface No heat and pressure involved Strata – layers of rock Stratification – the process in which sedimentary rocks are arranged in layers Sedimentary Rocks

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

This is a good example of Stratification

SEDIMENTARY ROCKS 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 MAY CONTAIN FOSSILS.

1.CLASTIC Sedimentary Rocks formed from the processes of weathering, erosion (transportation ), deposition, then lithification. 2.Lithification is the process of compaction and cementation of the clasts, or particles from weathering. THE 2 CLASSES OF SEDIMENTARY ROCKS

The 2 types of weathering include physical (only size changes) and chemical (a new substance is formed). Weathering

Sediments range in size from tiny pieces of clay to sand, to pebbles, and to stuff as big as boulders Sediments can be angular to rounded, and well or poorly sorted

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

Look at the processes that are occurring in this animation

Clastic Process

Examples of clastic sedimentary rocks include CONGLOMERATE BRECCIA SANDSTONE SHALE

Clastic sedimentary rocks are classified by their grain size, and shape of the grains.

Conglomerate – course, rounded clasts > 2mm Breccia – course, angular clasts >2mm Sandstone – clasts fine to course, >0.05 mm to <2 mm (cemented sand), occurs in many colors. Feels gritty. Common Clastic Rocks age3458.html

Common Clastic Rocks Siltstone – fine grained, clasts smaller than sandstone <0.05 mm, occurs in many colors due to composition or staining from surrounding minerals. Feels smooth or powdery Shale – made from clay, grains are small and flat. Breaks into thin pieces with sharp edges. Usually gray, brown, reddish brown or green.

2.Non-Clastic contain 2 types: chemical and biochemical Sedimentary Rocks made from mineral crystals that formed from chemical or biochemical deposition. 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

Limestone Cave 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 Examples of chemical sedimentary rocks include limestone and rock salt

BIOCHEMICAL OR ORGANIC Sedimentary Rocks are made from remains of once-living plants or animals (organic matter) COQUINA Made from shells CHALK Made from dead animals Biochemical sedimentary rocks include: coquina, chalk, coal and limestone this is the sedimentary rock type with the most fossils will be found near areas of lots of biological activity COAL Made from dead plants LIMESTONE with fossils in it

In Summation: 1. Sedimentary rocks form 3 ways: 1. _________ --compacted & cemented 2. _____________ : Chemically or Biochemically deposited 2. Sedimentary rocks are found in flat layers or _______ 3. _______ (remains of plants and animals) are found in Sedimentary Rocks. 4. ____________is formed both chemically and organically. Clastic strata Fossils Limestone Non-Clastic

5. Clastic rocks are made of _____________, examples are conglomerates, sandstone and shale 6.Chemically formed sedimentary rocks form from _____________ ocean water, which leaves behind evaporates like ___________, or from precipitates. 7.Some common sedimentary rocks are: sediments evaporating rock salt Shale, limestone, sandstone, siltstone, coal, chalk, coquina, breccia, conglomerate

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