Section 24.2: Resources from Earth’s Crust Pages 682 to 686

Land Resources Land provides the following: Space to grow crops Forests Grasslands Wilderness areas

Publicly Managed Land 828 million acres of land in the US is managed by federal, state and local governments. These areas have multiple uses including Recreational uses Grazing Mineral resources Energy resources National Forests – recreational areas as well as lumber (renewable) Wilderness areas – Protected wildlife area

National Parks These are protected areas that are used to sustain wilderness. These areas are used for recreation and the preservation of natural spaces

National Wildlife Refuges Protected habitats Breeding areas for wildlife Protection of endangered species (some) Some of these Refuges allow Fishing Trapping Farming Logging

Soil Top soil is important for the growth of crops Top Soil Loss This type of soil retains water and nutrients to enable plants to grow It can take up to 1000 years for soil to form Top Soil Loss It can be lost due to erosion Also clear cutting areas enable erosion to occur at a much higher rate On average 7% of the worlds top soil is lost each year

Soil Desertification Mini Video Lab Occurs when soil is lost in an area This can happen from over grazing, clear cutting and other human and animal activities When soil is lost the ground can no longer retain water and the area become arid Mini Video Lab https://www.youtube.com/watch?v=im4HVXMGI68 From the video why would raking leaves be problematic?

Aggregates They are naturally occurring products including Location Sand Gravel Crushed stone Location Accumulate naturally near or on the Earth’s surface Construction uses Cement, lime and other materials to produce concrete, mortar and asphalt Lava Rock can be used to prevent slipping on the ground when there is ice

Bedrock Is located underneath top soil and aggregate It consists of solid rock Limestone Granite Marble Other rocks It is used in construction and can be ground into aggregate

Ores Natural resources that can be mined for money The cost of gathering the mineral must be less than the profit made (that is you earn money) This means that a mineral that costs too much to gather would not be classified as an ore. Examples of ores: Gold and copper

Settling of Crystals (figure 8 image 1 page 685) Ores that are found at the bottom of a cooling Magma bed These crystals are only found in igneous rock Examples include Iron, Chromium and Platinum

Hydrothermal Fluids (Figure 8 Image 2 page 685) Includes most of the most important metals Metals like gold and copper take a long time to cool They fill the gaps/veins in rocks as they are fluids longer than the surrounding rock As the hydrothermal fluids reach the surface of the Earth they solidify

Chemical Precipitation (Figure 8 Image 3 Page 685) The formation of bands through chemical precipitation The exact process of these formations is not known They are believed to have formed during the Precambrian time period (Figure 1 Page 620)

Placer Deposits (Figure 8 Image 4 page 685) These deposits are found in places where current in the water slows For example when there is a curve in a river. This means that larger heavier sediments have the chance to sink and come to rest on the bottom Examples: Gold, diamonds, platinum, gemstones, tin and titanium oxides

Effects of Mining It can damage the environment physically and chemically It changes the contours of the land There is waste rock left behind Toxic chemicals can be released including mercury and arsenic This can affect ground and surface water causing it to no longer be potable Also Mining is one of the most dangerous occupations in the world and has the highest yearly death rate

Assignment Section Review Page 686 # 1 to 6