Identifying Rocks Sedimentary rocks

Rocks are partly identified by origin: Origin-beginning Original

Sedimentary Rocks

Wow! Seventy percent of all the rocks on earth are sedimentary rocks.

How are sedimentary rocks formed? Several Steps Erosion/weathered transported Deposition Compaction Cementation Burial

After burial, oldest rocks are found on the bottom.

Erosion/Weathering Occurs when running water or wind loosens and carries away fragments of rocks. Fragment –piece, bit

Erosion Erosion is the breakdown of the continents and the land around you.

Erosion is destructive!!! What causes erosion? Wind, water, heat, cold, rain, waves, grinding ice

Boulders become sand. Mountains are rained on and become hills. The pieces of the mountain become smaller pieces and go down the sides of hills. Weathering and erosion always happen in a downhill direction.

Fire Island Erosion

This is a sedimentary mark with ripples.

Wind, water, and glaciers transport the sediments.

Wind eroding and transporting

2. Deposition -when the sediments settle out of the wind or water. The Sediment will sink to bottom of lake or ocean

Oldest layers are on the bottom.

The sediments are deposited into a body of water like you are depositing money in a bank.

Deposition

Compaction It is a process. Thick layers of sediment build up Layers become heavy and press down on layers beneath Sediments are pressed together

Compaction

Compaction Diagram

After burial, oldest rocks are found on the bottom.

3. Cementation Word connection- cement – First, minerals in rock dissolve – Next, cement seeps into spaces between particles – Then, dissolved minerals crystallize and GLUE the particles together

See the cement? See the large pebbles?

Compaction and Cementation These processes cause loose sediments to turn into rocks This takes millions of years!!!!

grains of different sizes settle under the action of gravity. adding the pressure causes compaction (center). Cementation (right) is one of the final processes that turns sediment into rock.

Types of Sedimentary Rocks Clastic- formed by rock fragments squeezed together

Conglomerate

Conglomerate is a sedimentary rocksedimentary rock contains rounded particles/pebbles that are cemented together Has a large range of particle sizes

Organic made from living things (coral, clams, oysters, snails, shells, skeletons, leaves) – Coal – Limestone(chalk)

Organic Sedimentary Rock with Fossils

Types of sedimentary rock Sedimentary Clastic Conglomerate Breccia Sandstone Siltstone claystone Chemical crystalline limestone Organic Coal

Plant fossils

Chemical When minerals dissolve in a solution and crystallize Calcite to limestone Halite to mineral salt gypsum

In September, 2012, NASA's Mars Rover Curiosity discovered conglomerate rock on the surface Mars.

Martian Conglomerate: This image was acquired by NASA's Curiosity rover on the surface of Mars. It shows an outcrop of conglomerate and some pebble-size weathering debris. The round pebbles are too large to have been moved and shaped by wind, thus they had to have been transported by a significant distance by water. This photo from September 2012 was the strongest evidence of the existence of water on Mars that had been obtained at that time.