3Inner Structure of the Earth Inner Core—dense and solid4000 miles below surfaceOuter Core—Molten or liquidBoth are mostly hot and made of hot metal (iron)Appro 1,400 miles thick3. Mantle—thick layer of rock (1800 miles thick); mostly solid, but has pockets of magma (melted rock)
44. Crust—very thin layer; rocky surface Below the oceans, the crust is about 2 miles thick. Below the continents it averages 75 miles in thickness.
5Internal Forces that Shape Landforms Volcanoes—form when magma inside the earth breaks through the crust. Lava flows and may produce a large, cone-shaped mountain
6Divergent Plate Boundary Features FaultsEarthquakesIntrusionsVolcanoesCrust6Tasa Graphic Arts Inc.
72. Fault—a break in the earth’s crust 2. Fault—a break in the earth’s crust. Movement along a fault can send out shock waves, causing an earthquake.
9The Plate Tectonic Theory The lithosphere—the earth’s crust and upper layer of the mantle—are broken into a number of large, moving plates.The plates slide very slowly over a hot, pliable layer of mantle.3. The earth’s oceans and continents ride atop of the plates.
10Plate Boundary Features To view this animation, click “View” and then “Slide Show” on the top navigation bar.10
11The Ring of FireA circle of volcanic mountains that are surrounding the Pacific Plate
122. Hot Spots: hot regions deep within the mantle that produce magma, which rises to the surface. Volcanic island chains form as oceanic plates drift over the hot spot. Example: Hawaiian Islands.
20Subduction zone.*If an oceanic plate collides with a continental plate, the heavier oceanic plate will slide under the lighter, continental plate. Results: volcanic mountain building and earthquakes.
35Chemical WeatheringAlters the rock’s chemical make-up by changing the minerals that form the rock. Most important forces are water (H2O) and carbon dioxide (CO2).H2O + CO2 + CaCO3 --> Ca+2 + 2HCO3-
36Chemical WeatheringCarbonic Acid: CO2 from the air or soil combines with H2O to make carbonic acid. When the acidic water seeps into the cracks in certain rocks (limestone) it dissolves the rocks away. Examples: caves
37With the snow-draped Sierra Nevada as a backdrop, unique erosion formations called sand tufa stand like giant cauliflower stalks in a dry Arizona lake bed. Before this alkaline lake went dry, tufa formed when a freshwater spring percolated from below and formed calcium carbonate deposits. When the lake's level dropped, these fragile formations surfaced, and wind went to work removing the sand beneath the deposits.
38Chemical weatheringAcid Rain: Chemicals in the polluted water combine with water vapor and then fall back to the earth as acid rain.
39Acid Rain is known to be caused by industrial pollution, volcanic activity, and acid producing agents in the oceans.
40A stand of withered red spruce and Fraser fir trees blights a green vista in North Carolina's Mount Mitchell State Park.
41ErosionThe movement of weathered materials such as gravel, sand, and soil.An agent of mechanical weatheringThree common formsWindWaterGlaciers
42Erosion—Wind Most damaging in areas that are dry and with few plants Wind-blown sand carves and/or smooths natural and man made formations
43Desert winds sculpted these gentle swirls out of the limestone hills in Black Gap Wildlife Management Area, Texas. This remote, 100,000-acre (40,470-hectare) area in West Texas contains some of the lowest, driest, and hottest areas in the Chihuahuan Desert.
44Erosion—Water Moving water carries sediment Grinds away rock like sandpaperForms canyons and valleys
45Erosion—Glaciers Huge, slow moving sheets of ice When melted, leave behind piles of rock/debris called morainesGreat Lakes formed by glaciers
46The Bernard Glacier in Alaska's Saint Elias Mountains looks like a huge alpine highway. Glaciers are slow but highly effective shapers of the land, essentially carrying away anything in their path—from soil and rocks to hills and even the sides of mountains.