Presentation on theme: "3.3 Notes Sedimentary Rocks are Formed from Earlier Rocks."— Presentation transcript:
3.3 Notes Sedimentary Rocks are Formed from Earlier Rocks
Think About… What determines how rock pieces settle in water? If I pour sand and rocks into a jar, then _____ will sink to the bottom first because _________.
Some Rocks Form from Rock Particles If sand grains on a beach become cemented together, they form a sedimentary rock called sandstone.
Some Rocks Form from Rock Particles MOST sedimentary rock forms from loose material getting pressed together and cemented into rock.
Some Rocks Form from Rock Particles Sedimentary rock takes its name from the word sediment, which means “something that settles.”
Some Rocks Form from Rock Particles Sediments are materials that settle out of water or air.
Some Rocks Form from Rock Particles Pieces of plant and animal remains can make up sediments in addition to loose rocks and minerals.
Forming and Transporting Rock Particles Sediments can range in size from boulders to sand.
Forming and Transporting Rock Particles Rain washes away tiny rock pieces as it flows downhill. The water carries these particles to rivers which eventually empty into lakes or oceans.
Forming and Transporting Rock Particles Wind can also pick up sand and rock dust and carry them to distant places.
Forming Loose Sediments into Rocks As water or wind deposits stuff in layers, the layers eventually get buried by more layers. The layers on top press down on the layers underneath.
Forming Loose Sediments into Rocks Sometimes this pressure is enough to turn the layers into rock. Other times, minerals crystallize between the layers that cement them together.
Some Rocks Form from Plants or Shells Processes similar to the ones that produce sedimentary rocks from rock particles also produce rocks from shells or plant remains (fossils).
Coal If you look at a piece of coal through a magnifying glass, you may see shapes of wood or leaves.
Coal Coal is made up of remains of plants. That is why coal is called a “fossil fuel.” The coal we use today started forming millions of years ago.
Limestone Limestone is made of carbonate minerals such as calcite, found in organisms with shells.
Limestone When the organisms die, their shells settle on the ocean floor as sediment. Eventually, this sediment is formed into limestone.
Some Rocks Form When Dissolved Minerals Re-Form from Water Some sedimentary rocks are made up of minerals that crystallized as water dried up.
Some Rocks Form When Dissolved Minerals Re-Form from Water As water moves through limestone, some of the rock dissolves. This can eventually form huge open spaces (caves) in the rock.
Some Rocks Form When Dissolved Minerals Re-Form from Water As the water flows and drips through a cave, some of it evaporates, making many odd and beautiful shapes.
Some Rocks Form When Dissolved Minerals Re-Form from Water Sometimes minerals crystallize along the edge of lakes and oceans when the water evaporates. This is how salt and gypsum are both formed.
Sedimentary Rocks Show the Action of Wind and Water Sedimentary rocks are laid down in layers, with the oldest layers on the bottom.
Sedimentary Rocks Show the Action of Wind and Water Geologists can study these layers to know what Earth was like in the past.
Sedimentary Rocks Show the Action of Wind and Water The sediments also tell geologists what wind and water erosion were like in the past.
Sedimentary Rocks Show the Action of Wind and Water 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 Rocks Show the Action of Wind and Water This kind of rock layer is often created by a flood.
Sedimentary Rocks Show the Action of Wind and Water Sedimentary rocks also give information about the directions in which long ago wind or water currents were moving when sediments settled from them.
Sedimentary Rocks Show the Action of Wind and Water Rocks made of clay or silt that have cracks indicate they were formed during a wet period followed by a dry period.
Review 1.Pieces of rock can settle from water and get cemented into A.Metamorphic rock B.Sedimentary rock C.Igneous rock D.Extrusive rock
Review 2. Rock salt is an example of a sedimentary rock that develops from dissolved minerals as A.Water evaporates B.Magma cools C.Sediments break down D.Sand settles in water