physical Notes (2)

Forces the Shape our Planet External forces Weathering refers to the physical and chemical processes that change the characteristics or rocks. Sediment = smaller pieces of rock Mechanical Weathering is the process that breaks rock up into smaller pieces. Chemical Weathering occurs when rock is changed into a new substance as a result of interaction between elements in the air or water and the minerals in the rock.

Erosion = materials removed by the action of wind, water, ice, or gravity

Water Erosion Water Erosion -As water flows in a stream or river, it picks up loose material and moves it downstream. --- The force of a swift flowing river carrying sediment is enough to carve its way through rock forming a canyon. -- When a river enters the ocean, sediment is deposited into a fan-like landform called a delta. -- Wave action along coastlines also changes the land. Waves may build up beaches, or carry them away.

Wind Erosion This is quite similar to water erosion. The wind transports sediment and deposits it in other locations. Sand dunes are formed in this manner. The sediment carried in the wind may impact on solid objects causing erosion by abrasion. This can sculpt rock into columns and arches.

Glacial Erosion Glaciation is the changing of landforms by slowly moving glaciers. A glacier is a large, long-lasting mass of ice that moves because of gravity. Glaciers form in mountainous areas and in regions that are regularly covered with heavy snowfall and ice. On top of the glacier or inside it are other rocks. When the ice melts, these are left behind. Rocks left behind by a glacier may form a ridge or a hill. As a glacier moves it can carve flat plains or valleys. Sometimes blocks of ice are trapped in the sediment. They melt slowly and leave a depression called a kettle lake.

The Earth’s Water *The ocean is an interconnected body of salt water that covers about 71 percent of our planet. *The four oceans are the Atlantic, Pacific, Indian, and the Arctic Ocean. *The salty water of the ocean circulates through three basic motions: currents, waves, and tides

How much water do we really have? 97% of the worlds water is found in oceans. This water is too salty for drinking and farming. 2% of the world’s water supply is fresh but frozen in glaciers and ice caps. This leaves only another 0.5% is under the earth’s surface (Groundwater). Aquifers are underground layers of porous rock that is saturated with water and acts like and underground stream. Less than 1% in the world’s water is found rivers, lakes, and streams. Even thought very little water is found here they are very important to survival, agriculture, and transportation.

What does that mean?

Hydrologic Cycle The hydrologic cycle is the continuous circulation of water between the atmosphere, the oceans, and the earth. Water evaporates into the atmosphere. The water in the atmosphere exists as vapor. When the vapor cools, it condenses.  Water vapor in the atmosphere can become precipitation, falling water droplets, in the form of rain, sleet, snow, or hail.

Time to make your own Hydrologic Cycle!!!