Notes Sedimentary Rocks

Think About What do you think would settle to the bottom of a body of water faster, rocks or sand? Why?

Clastic Sedimentary Rock MOST sedimentary rock forms from sediment getting pressed together and cemented into rock.

Clastic Sedimentary Rock Sedimentary rock takes its name from the word sediment, which means “something that settles.”

Clastic Sedimentary Rock Sediments are loose materials that settle out of water or air.

Clastic Sedimentary Rock Sediments can range in size from boulders to sand.

Clastic Sedimentary Rock Rain washes away tiny rock pieces as it flows downhill. The water carries these particles to rivers which eventually empty into lakes or oceans.

Clastic Sedimentary Rock Wind can also pick up sand and rock dust and carry them far away.

Clastic Sedimentary Rock As water or wind makes layers of sediment, the layers eventually get buried by more layers. The layers on top press down on the layers underneath.

Clastic Sedimentary Rock Sometimes this pressure alone is enough to turn the layers into rock. Other times, minerals also crystallize between the layers and cement them together.

Clastic Sedimentary Rock Sedimentary rock formed from loose rock particles is called clastic sedimentary rock.

Clastic Sedimentary Rock If sand grains on a beach become cemented together, they form a sedimentary rock called sandstone.

Organic Sedimentary Rock Small pieces of plant and animal remains can also be found in sediment.

Organic Sedimentary Rock Sedimentary rocks can be made from broken down shells or plant remains (fossils).

Organic Sedimentary Rock If you look at a piece of coal, you can sometimes see shapes of wood or leaves.

Organic Sedimentary Rock Coal is made up of plant remains. That is why coal is called a “fossil fuel.” The coal we use today started forming millions of years ago.

Organic Sedimentary Rock Limestone is made of minerals such as calcite, found in organisms with shells.

Organic Sedimentary Rock When shelled organisms die, their shells pile up and break down on the ocean floor. Eventually, this sediment is formed into limestone.

Organic Sedimentary Rock Sedimentary rock formed from fossils is called organic sedimentary rock.

Chemical Sedimentary Rock Some sedimentary rocks are made up of minerals that crystallize as water evaporates.

Chemical Sedimentary Rock As water moves through limestone, some of the rock dissolves. This can form open spaces (caves) in the rock.

Chemical Sedimentary Rock As the water flows and drips through a cave, some of it evaporates, making many odd and beautiful shapes.

Chemical Sedimentary Rock Sometimes minerals crystallize along the edge of lakes and oceans when the water evaporates. This is how salt and gypsum are both formed.

Chemical Sedimentary Rock Sedimentary rock formed by the evaporation of water is called chemical sedimentary rock.

Sedimentary Rock Formations Sedimentary rocks are formed in layers, with the oldest layers on the bottom.

Sedimentary Rock Formations Geologists can study these layers to know what Earth was like in the past.

Sedimentary Rock Formations The sediments can tell geologists what wind and water erosion were like in the past.

Sedimentary Rock Formations A rock layer with large particles on the bottom and small particles on the top indicate that the water carrying the sediment was slowing down.

Sedimentary Rock Formations This kind of rock layer is often created by a flood.

Sedimentary Rock Formations Rocks can also show the direction wind or water currents were moving when sediments settled from them.

Sedimentary Rock Formations Rocks made of clay or silt with cracks indicate they were formed during a wet period followed by a dry period.

Pieces of rock can settle from water and get cemented into Review Pieces of rock can settle from water and get cemented into Metamorphic rock Sedimentary rock Igneous rock Extrusive rock

Review 2. Rock salt is an example of a sedimentary rock that develops from dissolved minerals as Water evaporates Magma cools Sediments break down Sand settles in water

Review 3. When hiking outdoors you notice an object and pick it up. You observe the following characteristics: the object is black in color, has a rough texture, dull in luster, and contains organic matter. What is the object you are holding? Obsidian Quartz Coal Magnetite