29.2 The Surface of Earth Earth’s surface is constantly changing. Recall that earthquakes, volcanoes, mountains, and the construction of new lithosphere are events that occur at plate boundaries. These events are changing the appearance of Earth’s surface all the time.
*Thefeatures we see on Earth’s surface represent the dynamic balance between constructive processes versus destructive processes.
29.2 Mountain Building *Mountain-building is a major constructive process. *Mountains form in three main ways: — by folding at convergent plate boundaries — by movement of chunks of land at faults — by volcanic activity
Mountain Building Processes:*Fold Mountains: Form as two convergentplate boundaries collide Example: the Himalayas (Mt. Everest)
Mountain Building Processes:*Fault Block Mountains- Pressure at plateboundaries cause the lithosphere tocrack and pieces of it tilt or move causinga valleys and tilt mountainsExample: mountains around San Andreas Fault
Mountain Building Processes:*Volcanic Mountains- Extensive layeringof lava and volcanic material builds upover time to form a dome mountain. Example: Mount Rushmore
Destructive Processes *Erosion- (also known as weathering) is a major destructive process. *Erosion is a continuous physical and chemical event that cause land and rock to wear down. The rate of erosion is related to the height and steepness of the mountain—the steeper the mountain is, the faster it erodes because it is easier to push material down a steep slope than a gradual slope.
Formation of Soil *A soil profile is a cross-section that shows the different layers of soil in the ground. It takes a long time and a lot of weathering for soil to have all the layers. Young soil does not have each of these layers.
Glaciers *A glacier is a huge mass of ice that can be many kilometers thick and thousands of kilometers wide. Glaciers at the poles are a frozen form of about 2 percent of all the water on Earth. Glaciers are formed from the accumulation of snow over hundreds or thousands of years.
Your turn:Read section 29.2 pgs 568-575and add to your notes.
Rocks and Rock Cycle *Arock is a naturally formed solid usually made of one or more minerals. Theterms igneous, sedimentary, and metamorphic refer to how a rock was formed. Therock cycle illustrates the formation and recycling of rocks by geological processes.
Igneous Rocks *IgneousRocks are made of magma or lava — Intrusive igneous rocks are formed below Earth’s surface — Extrusive igneous rocks are formed above Earth’s surface
Sedimentary Rocks *Sedimentary Rocks- rocks that form from sediment that is compressed and cemented over a long period of time
Metamorphic Rocks *MetamorphicRocks- a rock that is transformed by tremendous heat and pressure
Answer On Your Paper: Is erosion a constructive or destructive force that shapes the land? — Explain your answer.