Sedimentary Rocks
Do a Google Search... Write 2 interesting facts about sedimentary rocks?
1. The sedimentary rock, selenite is used for fertilizer and paint filler. 2. The sedimentary rock, coal, especially mined in the eastern US, contains so much sulfur that when it is burned, the sulfur in the smoke forms sulfuric acid. Unless the sulfur is removed by scrubbers at the power plant, it contributes greatly to acid rain.
Explain how a clastic rock is formed.
A clastic rock is a sedimentary rock formed when rock fragments are squeezed together.
Explain the process of erosion.
After a rock has been weathered and broken up, the fragments are carried away as a result of erosion - the process by which running water, wind, or ice carry away bits of broken-up rock.
Explain how chemical rock is formed.
Chemical rock forms when minerals dissolved in a water solution crystallize. Chemical rocks can also form from mineral deposits that are left when seas or lakes evaporate.
What are 2 examples of organic sedimentary rocks?
Coal and limestone.
How does coal form? Where does it form?
Coal forms from the remains of swamp plants buried in water. As layer upon layer of plant remains build up, the weight of the layers squeezes the decaying plants together. Over millions of years, they slowly change into coal.
People have used sedimentary rocks throughout history for many different purposes. Explain the practical uses of flint, sandstone, and limestone.
For thousands of years, people used flint to make arrowheads. Today, builders use sandstone and limestone on the outside walls if building. Limestone also has industrial uses. For example, it is used in making cement and steel.
How do geologists classify sedimentary rocks?
Geologists classify sedimentary rocks according to the type of sediments that make up the rock.
How does limestone form? Where does it form?
Limestone forms in the ocean, where many living things, such as coral, clams, and oysters, have hard shells or skeletons made of calcite. When these ocean animals die, their shells pile up on the ocean floor. Over millions of years, compaction and cementation can change the thick sediment into limestone.
Explain how limestone can be both chemical and organic.
Limestone is organic because when it is compacted and cemented there are dead organisms that used to be living in it. Limestone can also form when calcite that is dissolved in lakes, seas, or underground water comes out of a solution and forms crystals. This kind of limestone is considered a chemical rock.
What is the 5 step sequence of processes that leads to the formation of sedimentary rocks?
Most sedimentary rocks are formed through a sequence of processes: weathering, erosion, deposition, compaction, and cementation.
What are most sedimentary rocks made of?
Most sedimentary rocks are made up of broken pieces of other rocks.
Explain how organic sedimentary rocks are formed.
Organic rock forms where the remains of plants and animals are deposited in layers.
Give the example from the book of how rock salt is formed.
Rock salt is made of the mineral halite, which forms by evaporation.
Organic Rock
Sedimentary rock that forms from remains of organisms deposited in thick layers.
Chemical Rock
Sedimentary rock that forms when minerals crystalize from a solution.
Clastic Rock
Sedimentary rock that forms when rock fragments are squeezed together under high pressure.
Explain how sediments form.
Sedimentary rocks form when sediment is deposited by water and wind.
Contrast how fragment size varies with following sedimentary rocks: shale, sandstone, conglomerate, and breccia.
Shale forms from tiny particles of clay. Fossils are often found in shale, which tends to split into flat pieces. Many small holes between sand grains allow sandstone to absorb water. Most of the sand particles consist of quartz. Rock fragments with rounded edges make up conglomerate. Rock fragments with sharp edges form breccia.
Name 4 common clastic sedimentary rocks that have different rock fragment sizes.
Shale, sandstone, conglomerate, and breccia.
Sediment
Small, solid pieces of material that come from rocks or the remains of organisms; earth materials deposited by earth deposited by erosion.
Why are organic sedimentary rocks named "organic"?
The term "organic" refers to substances that once were part of living things or were made by living things.
Explain the process of compaction.
Thick layer of sediment build up progressively over years. The weight of new layers can squeeze older sediments tightly together. The process that presses sediments together is compaction.
Explain the process of deposition.
Water can carry sediment to a lake or ocean. Here, the material is deposited in layers as it sinks to the bottom. Deposition is the process by which sediment settles out of the water or wind carrying it.
Explain the process of weathering.
Weathering - the effects of freezing and thawing, plant roots, acid, and other forces on rock, constantly breaks up rock on Earth's surface. After the rock is broken up the fragments are carried away by erosion.
Explain the process of cementation.
While compaction is taking place, some minerals in the rock slowly dissolve in the water. Cementation is the process in which dissolved minerals crystallize and glue particles of sediment together.
Strata
a layer or single bed of sedimentary rock
What are the 3 major groups/classifications of sedimentary rocks?
i. Clastic Rocks ii. Organic Rocks iii. Chemical Rocks
Tiny grains of sand, mud, pebbles, shells leaves, and even bone are examples of
sediment.
Clastic rocks are grouped by the ______ of the rock fragments they contain.
size
Stratification
the arrangement of sedimentary rocks being layered, each layer representing the sediment deposited over a specific period
Instead of forming by particles of rock, coal and limestone form from
the remains of material that was once living.
