Earth and Space ScienceMs. Pollock

2010 - 2011

Built across Colorado River near Las Vegas in 1930s

Built to supply water and electricity to arid (dry) lands

Also affects environment

Disruption to normal river flow

Flooding from reservoir behind dam

Water deprivation downstream from dam

Useful resources contained in Earth’s crust

Formation of many resources takes millions of years

Over 3,000 identified minerals Can be metals or nonmetals

Metallic minerals also called native elements

Most minerals found in compound form, as they are unstable

Ores are mineral deposits from which metals and nonmetals can be removed profitably.

Iron ore from hematite or magnetite

Aluminum ore from bauxite

Mercury ore from cannabar

As magma cools, dense metallic minerals sink and accumulate at the bottom of magma chambers to form ore deposits.• Chromium• Nickel• lead

Magma in contact with existing rock Can be caused by hydrothermal

solutions (hot water) passing through cracks in rock

Hydrothermal solutions cause formation of veins – narrow zones of ores.

Lode – many thick mineral veins formed in small region

Gold vein in Zamibia

Silver lode deposit locations in British Columbia

Tiny fragments of native elements released from rock as it is broken down by weathering

Fragments carried downstream by moving water

Placer deposit – concentration of fragments of native element at bottom of stream bed

See page 157 in your textbook – Table 1

Some metals prized for beauty and rarity

Some nonmetals considered gemstones

Some building materials

Companies often in search of new mining areas

Area only good for mining if it contains 100 to 1,000 times the amount of mineral found elsewhere

Local geology a factor• Aerial studies of magnetism, gravity,

radioactivity, and rock color• Collection and testing of rock samples

Many mineral deposits located below Earth’s surface

Miners working underground to recover the minerals

Mineral deposits located close to Earth’s surface

Overlying rock stripped away to reveal mineral deposits

Mined by dredging Large buckets

attached to floating barge

Sediments scooped up in front of barge

Dense placer deposits separated and sediments released into water

Nodules – lumps of minerals on deep-ocean floor

Difficult to mine due to location• Iron• Manganese• nickel

Complete page 158 # 1 – 7. You do not need to write the

question.