large rocks can split when water seeps into small cracks freezes and expands .the chemical properties of newly formed fragments of rocks are
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Background: Weathering
The processes of weathering and erosion are similar, but not the same. Weathering is the gradual breaking down of rocks into smaller pieces caused by the action of weather conditions. Plant and animal life, atmosphere and water can cause weathering effects. When weathering occurs, the rock stays in the same place. The particles removed are called sediments.
As soon as rock sediments begin to move, erosion takes place. Erosion is a process that transports rock, soil and sediment to a different location. Erosion can occur on its own, but it more often happens after weathering occurs. Weathering and erosion often create amazing landscape features.
Types of Rocks
All rocks are made up of minerals. Geologists (scientists who study rocks) classify rocks into three basic types: igneous, metamorphic and sedimentary.
Igneous rocks are created from superheated liquids that originate deep within the earth. They are formed from hot, molten rock known as magma. The magma cools and hardens after it comes to the surface. Granite is an example of an igneous rock.
Metamorphic rocks are rocks that have changed due to heat and/or pressure. Marble is an example of a metamorphic rock.
Sedimentary rocks are created when sediments are deposited and compressed or cemented together by lime, silica, etc. Sedimentary rocks make up about three-quarters of the rocks on the earth’s surface. Limestone is an example of a sedimentary rock.
Types of Weathering
Mechanical weathering takes place when rocks are broken down without any change in the chemical nature of the rocks. The main cause of weathering is extreme changes in temperature. One example is that there might be a crack in a rock. Rain can then seep into the crack and expand as it freezes. This causes small cracks in the rock to grow larger, forcing the rock to split apart. Extreme heat causes rocks to expand. When the weather cools, the rock weakens and eventually breaks apart.
Another type of weathering is salt weathering. As water enters the holes and cracks in the surface of rocks, it often carries salt with it. As the water later evaporates, the salt is left behind. Over time, these salt deposits build up, creating pressure that can cause rocks to split and weaken.
Chemical weathering occurs when the minerals that make up a rock are dissolved or chemically changed. These chemical reactions can break down the bonds holding the rocks together, causing them to fall apart. Water can also be absorbed into the minerals in the rock. The rock then expands and is weakened. Sometimes rainwater contains acid (acid rain). When this comes in contact with rocks such as limestone, it slowly dissolves the rock.
The most common forms of weathering are oxidation, hydrolysis and carbonation.
Oxidation occurs when oxygen combines with other elements, creating new kinds of rocks.
Hydrolysis occurs when water combines with substances in the rock, forming new kinds of substances.
Carbonation occurs when carbon dioxide reacts with rocks, forming a solution that is then carried away by water.