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About Sedimentation

Sediments are produced on the Earthssurface as a result of weathering.

Sediments are transported and becomesedimentary rocks after they come torest.

Sedimentary rocks give evidence ofancient sedimentary environments wherethey formed.

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magma crystallization

weatheringand erosion

deposition

deformation

melting

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The Rock Cycle

Full cycle does not always take place due to"shortcuts" or interruptions e.g., Sedimentary rock melts e.g., Igneous rock is metamorphosed

e.g., Sedimentary rock is weathered e.g., Metamorphic rock weathers

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Three Rock Types

Igneous - cools and crystallizes frommagma; intrusive and extrusive

Sedimentary - deposited at Earths surface

by physical, chemical, or biologic agentsand then buried

Metamorphic - rocks formed by the

transformation of preexisting solid rocksdue to changes in temperature andpressure

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Igneous Rocks in North America

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Sedimentary Rocks in North America

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Metamorphic Rocks in North America

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Sedimentary Rocks Form from sediment (weathered products) About 75% of all rock outcrops on the continents Used to reconstruct much of Earth's history

Clues to past environments

Provide information aboutsediment transport

Rocks often contain fossils

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Sedimentary Rocks

Economic importance Coal Petroleum and natural gas

Sources of iron and aluminum

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Sedimentary Rock Classification

Two groups based on the source of thematerial

Detrital rocks or siliclastic

Material is solid particles Classified by particle size Common rocks include

Shale (most abundant)

Sandstone Conglomerate

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Sedimentary Rock Classification

Chemical or Biochemical rocks Derived from material that was once in solutionand precipitates to form sediment

Directly precipitated as the result of physical

processes, or Through life processes (biochemical origin) Common rocks include

Limestone

Microcrystalline quartz(chert, flint, etc.)

Evaporites (salt, gypsum) Coal

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Sedimentary Rock Classification

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Detrital Sedimentary Rocks

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Chemical Sedimentary Rocks

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Lithification Sedimentary rocks are produced

through lithification Loose sediments are transformed into solid

rock

Lithification processes Compaction Cementation by

Calcite Silica Iron Oxide

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the sorting of sediments can indicate how far the rock has been

transported

Sediment Sorting

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coal is produced bythe burial and compaction(lithification) of organicmaterial

different pressure andtemperature conditionsyield different qualities of

coal

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Features of Sedimentary Rocks Strata, or beds (most characteristic) Bedding planes separate strata Fossils

Traces or remains of prehistoric life

Are the most important inclusions Help determine past environments Used as time indicators Used for matching

rocks from differentplaces

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