50 likes | 233 Views
Resources from the Earth’s Crust. Chapter 24.2. Land Resources Public Land - more than 828 million acres of public land in the U.S. - include national parks, preserves, and wildlife refuges. Top Soil - it can take up to 500 years to form 1 centimeter of topsoil.
E N D
Resources from the Earth’s Crust Chapter 24.2
Land Resources Public Land - more than 828 million acres of public land in the U.S. - include national parks, preserves, and wildlife refuges. Top Soil - it can take up to 500 years to form 1 centimeter of topsoil. - without plant roots to hold it in place, wind or water can remove it. - loss of topsoil can lead to desertification. - especially a problem in arid regions such as Africa, Western U.S., Australia, & Middle East.
Aggregates - sand, gravel, & crushed stone - used in construction (mixed with cement to make concrete) Bedrock - layers of rock that can be quarried and used in homes & buildings (flooring, counter tops, block walls) Ores - ‘mineral-containing’ rock that can be mined for profit.
Effects of Mining Surface mining - removal of overlying material to expose ore. - alters landscape - exposes surface to toxic substances. Underground mining - digging of tunnels to area of ore to be removed. - especially dangerous to miners - surface may be vulnerable to sink holes Tailings - material left behind after ore is extracted from rock. - may contain harmful substances that contaminate soil or groundwater. Video – McCaw School of Mines