Human Impacts on Lithosphere

Dust Bowl In the 1930’s a terrible drought and huge windstorms blew away much of the topsoil. The entire central United States was affected.

Causes of Soil Erosion Soil erosion is caused by the same things that cause erosion in general: water, wind, ice or gravity. Running water is the leading cause of soil erosion. Activities that remove vegetation, disturb the ground or allow the ground to dry can increase erosion.

Human Activities that Increase Soil Erosion Farming Grazing Logging/Deforestation Mining Construction/Urbanization Recreational Activities

Farming Agriculture - the production of food and fiber from plants and animals. One of the biggest causes of soil erosion because of the huge amount of land that is needed to produce food. In this production the soil is disturbed in order to plant crops, harvest crops and prepare fields for new crops.

Grazing Grazing – plant eating animals wander over large areas eating the vegetation. The animals expose the soil to erosion when they remove the plants or tear up the soil with their hooves. Overgrazing – when there are too many animals grazing an area for the amount of plants in the area.

Logging/Deforestation Logging is the harvesting of trees for the production of lumber or wood products. Deforestation is the cutting of trees and loss of forests. Trees roots hold the soil together and the canopy protects the soil from hard falling rain. Leaf litter – dead leaves, bark and branches on the forest floor that protect soils from erosion.

Mining Mining – the removal of valuable resources from the Earth Surface mining disturbs the land and leaves soil vulnerable to erosion.

Construction/Urbanization Urbanization – the building and growing of cities. Constructing buildings and roads churns up the ground, exposing it to soil erosion. Water running off of parking lots and across nearby land speeds up erosion in those areas.

Recreational Activites Off-road vehicles disturb the landscape and the area eventually develops bare spots where no plants can grow. Even hikers’ boots can disturb the ground.

Soil Erosion Soil erosion is as natural as any other type of erosion, but human activities have greatly accelerated soil erosion. In some locations soil erosion may occur about 10 times faster than its natural rate. Since Europeans settled in North America, about 1/3 of the topsoil in the area that in now the United States has eroded away.

Geohazards and Precautions Earth/Environmental Science

What is a Geohazard any natural hazard that is caused by the Earth Landslides Earthquakes Tsunami Flooding

Landslides Rapid downslope movement of Earth materials. Caused by heavy rainfall, flood, earthquake, erosion, and human activities

Precautions Avoid building on steep, unstable slopes. Cover the slopes with metal netting. Build retaining wall at bottom of slope. Education

Earthquakes Precautions The sudden shaking of the Earth. Buildings should meet earthquake construction requirements. Have heavy items close to the ground. Precautions

Tsunami Precaution A giant wave caused by an underwater earthquake. Listen to news for a warning Move away from the shore and to higher ground Do not go to the beach even if you see water receding Precaution

Flooding Natural event when water flows over the banks of rivers. Recognize clues such as heavy rains, topography and flood history. Learn evacuation routes. Keep vehicle fueled since power failure may render service stations inoperable. Precautions