SEDIMENTARY ROCKS

Unit 1: Sixth Grade

HOW SEDIMENTARY ROCKS FORM…

Wind, water, ice, sunlight, and gravity cause rocks to weather into sediments.

These sediments are moved from one location to another by the process of erosion.

Erosion: The movement of the material from one place to another

FORMATION OF SEDIMENTARY ROCKS

The sediments are eventually deposited on to older layers and form new ones.

The sediments become compacted and dissolved minerals separate from water and form a natural cement—Lithification.

Sedimentary rocks are formed

STRATA AND STRATIFICATION

STRATA Layers of rock

STRATIFICATION process in

which sedimentary rocks are arranged in layers

HOW ARE WERE THE STRIPES FORMED?

Wind blew over thousands of years

Carried mineral/rock fragments, “sand” to ocean floors, lakes rivers

The sand mixes with quartz or calcite.

Pressure over time causes them to become rock

HOW ARE THE STRIPES FORMED?

But not all sand is the same!

Over millions of years, smaller grains separated from the larger grains and were layered on the bottome

PETRA

Why do you think there are so many colors in the stone?

Can you describe the pattern on this structure?

Does this structure support the idea that layers of sediments piled on top of each other and exposed to heat and pressure form sedimentary rock?

ORGANIC SEDIMENTARY ROCKS

Form from remains or fossils of once living things.

EXAMPLE: limestone, coal

COAL---- Forms underground when

partially decomposed plant material is buried beneath sediment and is changed into coal the pressure from layers above.

This process takes millions for years.

Non-renewable fossil fuel

CLASTIC SEDIMENTARY ROCKS

Made from fragments (sediments) of rocks that are cemented together by minerals .

They are classified according to the size of the fragments.

EXAMPLES: conglomerate, sandstone, siltstone, shale

Loose sediments

Clastic Sedimentary Rock

CHEMICAL SEDIMENTARY ROCKS

Form from solutions of dissolved minerals and water.

EXAMPLE: halite