Chapter 8: Changes to Earth’s surface. Lesson 2: What causes changes to Earth’s Landforms?

Glacier- A large moving block of ice. Volcano- A mountain that forms as lava flows through a crack onto Earth’s surface. Earthquake- The shaking of Earth’s surface caused by movement of rock in the crust. Deposition- The dropping of bits of rock and soil by a river as it flows. Glacier- A large moving block of ice. Earth has four layers: crust, mantle, outer core, inner core Crust- Earth’s thin outer layer that we walk on everyday. Sits on top of the mantle. Mantle- Rock layer below the crust. Earth’s thickest layer. Core- Earth’s center, made mostly of iron and nickel. Divided into two sections. Outer core and Inner core Outer core is liquid Inner core is solid due to pressure Earth’s crust is broken into many large slabs of rock called plates.

Mountain chains can form when two land plates collide. There are different types of volcanoes such as: Composite volcanoes- made of layers of lava, rock, and ash. They can have steep peaks and are usually explosive when they erupt. Hawaii has Shield volcanoes- huge mountains that erupt slowly and lava flows steadily down their gently sloping sides. Cinder cone volcanoes- small and have steep sides. They shoot cinders, ash and chunks of rock into the air and down their slopes. When two ocean plates push together, one if forced under the other. The upper plate melts and forms magma, the magma rises and forms volcanoes. Magma is melted rock. https://video.search.yahoo.com/search/video;_ylt=AwrBT7g8RIpaepEAhQBXNyo A;_ylu=X3oDMTB0N2Noc21lBGNvbG8DYmYxBHBvcwMxBHZ0aWQDBHNlYwNwa XZz?p=volcanoes&fr2=piv- web&fr=skyh#id=10&vid=2aa2c4f04e70991c27752d9fd564bc3b&action=view The movement between two plates can cause earthquakes. Most earthquakes occur along faults due to the movement of rock along faults. A fault is a break in the crust, where rock moves. http://www.harcourtschool.com/activity/science_up_close/418/deploy/interface .html

Rivers flow through valleys. Older rivers often have wide valleys with flat floors. They flow through the valleys in wide curves. Rivers that flow down steep slopes can cut deep valleys causing deposition to increase. Deposition builds landforms such as deltas and floodplains. Snow piles up and packs down until a large mass of ice forms. When this mass of ice moves, it becomes a glacier. Two main types of glaciers are – alpine glaciers and ice sheets. Alpine glaciers- flow down mountain valleys. The glacier widens the valley giving it a U-shape. Ice sheets – huge glaciers that cover large areas, such as Antarctica and Greenland. For wind erosion to occur, conditions must be dry and windy where soil is loose and can be easily moved.

Test Prep Question: What evidence of wave erosion might be seen in landforms along the shore? Landforms that show erosion and deposition includes beaches, barrier islands, sandbars, crumbling cliffs, and offshore rock formations such as arches and pillars (sea stacks).