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Aim: How do sedimentary rocks form?

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Do Now: Predict how each sediment will settle in a jar full of water:SandPebblesRocksSoil

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A. Sediments in water deposit with the largest first, then the smallest

Rocks (heaviest settle on bottom)

Pebbles Sand may fill in

the gaps Soil (smallest

lays on top, may also float in suspension)

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Sediment sizes can be found on this ESRT chart:

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Definitions: Sediment Weathering Erosion Deposition Compaction Cementation Clastic Fossil

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B. What are sedimentary rocks made from? Sedimentary rocks form

from pieces of existing rock that have been worn away (weathered), carried to new place (erosion) and deposited there (deposition).

These pieces of rock are called sediments.

Water, ice, gravity, and wind are the agents of erosion.

Most sedimentary rocks form in water.

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C. How do deposited sediments form rocks?

Sediments settle loosely.

More sediments settle on top and press them together (compaction)

Over years, more layers of sediments settle and get compacted.

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In sedimentary rock formations, where would you find the oldest layers?

Older layers form on the bottom unless they have been uplifted or tilted by movement of the crust!

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D. What holds the sediments together?

Minerals in the sediments dissolve in water and seep into the spaces between the sediments.

The minerals form a “glue” that hold the sediments together. (cementation).

Watch sedimentary rocks form

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Trace the path of an igneous rock to a sedimentary rock. What other kinds of rock can become sedimentary?

UPLIFT means that a rock must be pushed up toward the surface where weathering takes place in order to become a sediment

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Aim: What are the 3 ways sedimentary rocks form?

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E. Three processes that form sedimentary rocks: 1. Clastic – rock fragments held together

Examples: shale, sandstone, conglomerate

2. Organic (bioclastic) – remains of plants and animals deposited in thick layers, can contain fossils Examples: Coal, limestone (fossil or coquina)

3. Chemical – minerals dissolved in water re-crystallize into rocks when water evaporatesExamples: halite (rock salt), rock gypsum, chalky limestone

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F. Clastic Examples – sediments with different sizes (usually more than 1 mineral)

Breccia – big sharp sediments

Conglomerate -big rounded sediments

Sandstone – sand sized sediments

Siltstone - silt

Shale –mud, clay

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G. Organic Examples (bioclastic) : Limestone It is usually an

organic sedimentary rock that forms from the accumulation of shell, coral, algal and fecal debris. Always forms in water.

Only 1 mineral

limestone

coquina

Fossil limestone

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G. Organic Examples: Coal

Coal is formed by plant debris piling up in water.

http://www.classzone.com/books/earth_science/terc/content/visualizations/es0701/es0701page01.cfm?chapter_no=07

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H. Chemical: Crystaline

Formed from precipitation or evaporation in water

Only 1 mineral

Rock Salt – evaporite, sedimentary form of mineral halite

Rock Gypsum – precipitate form of mineral gypsum

Dolostone – precipitate form of mineral dolomite

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I. Sedimentary Rocks:

Are the most abundant kind of rock on the outer surface (75%+).

Trap a history of the earth in the layers of rock. (life forms, climate and natural events)

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J. Grand Canyon

http://www.youtube.com/watch?v=XckLEPTmKjA&feature=related

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Describe some characteristics a sedimentary rock might have:

Layers Sand particles Pebbles –round or jagged Fossils Crystals

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Label the sedimentary rock as organic, clastic or chemical.

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