Earth Resources Geology—study of dynamic processes in the earth’s surface & interior Slow processes, with occasional rapid events Geologic time Billions of years Change is rule, not exception Earth Golf ball-ish, peanut M & M Core, mantle, crust Earth Core Innermost zone Intensely hot Solid inner part Surrounded by liquid core—molten or semi-solid material Mantle Thick Outermost—solid rock Underneath—hot, semisolid rock, flows slowly: asthenosphere Asthenosphere—plastic: can be deformed Outermost Thinnest Crust Continental crust—29% of earth’s surface Oceanic crust—71% of earth’s surface Geologic Processes Changes on crust reflect internal processes Interior processes—changes in interior Heat, gravity Core cooling—heat released as inner core cools Outer core—cools and solidifies Asthenosphere Geologic Processes Convection cells—move heat and rock in conveyor belt motion— hot rock rises, cool rock downward Mantle plumes—mantle rock moves upward in vertical column, fans out Plate Tectonics Tectonic plates—solid, rigid plates: 15 Continental and oceanic crusts and outermost portion of mantle—lithosphere Move slowly, on asthenosphere Range from 1 cm -> 18 cm Move apart and slam into each other Create mountains, ridges and trenches Video clip Plate Tectonics Plate Boundaries Divergent—plates move away Convergent—plates pushed together Oceanic plate runs into continental—continental over oceanic Subduction—distinct subduction zones Transform Fault—plates slide past each other Why Study This Explains distribution of plant and animal life Provides insight into distribution and location of valuable materials May explain mass extinctions—ocean movements, heat redistribution Minerals and Rocks Minerals—elements or inorganic compounds, natural, regular internal crystalline structure Rock—combination of one or more minerals, most have more than mineral Rock types—igneous, sedimentary, metamorphic Igneous Rock Formed below or on surface Magma rises up from mantle, cools, hardens Granite—below Lava—above Bulk of crust Covered with soil, sedimentary rocks Source of non-fuel mineral resources Weathering Exposure to air, water, temperature change, reactive chemicals Rock breaks down Mechanical—no chemical change Chemical—selective removal of components weakens rocks Small pieces transported by air, water gravity Sedimentary Rock Formed from sediment Weathered rock Water, wind, gravity, ice Deposited in layers, accumulate Pressure & dissolved minerals bind sediment Sandstone, shale, dolomite, limestone, lignite, bituminous coal Metamorphic Rock Preexisting rock is subjected to high temperatures, high pressures, chemically active fluids, or combination Change structure, physical properties, appearance Anthracite, slate, marble Rock Cycle Cycling of rock types Millions of years Concentrates non-renewable resources So What? We use rocks and minerals—resources Metals—lightness, strength, malleability: tools and machines Non-metals—salt, clay, sand, phosphates Energy—coal, oil, natural gas, uranium Resources Nonrenewable—take long time to produce More than 100 nonrenewable resources Ore—rock containing enough resource to make mining profitable USGS Nonrenewable Identified resource—known location, quantity & quality, or existence based on known evidence Reserves—identified resources usable resource extracted profitably at today’s prices USGS (cont’d) Undiscovered—potential supplies assumed to exist on basis of geologic knowledge and theory, unknown specific location, quantity, quality Other—undiscovered resources and discovered resources that are not reserves Resource Identification Aerial and satellite photos Radiation sensing Magnetometer Gravimeter Seismic Chemical analysis Shallow deposits Extraction Surface mining Remove overburden Waste soil and rocks—spoils Extraction Topography and resource determine method Open-pit Dredging Area strip Contour strip Mountain top removal Placer Reclaimed mines Expensive Partially successful Extraction Subsurface mining—deep deposits Vertical shafts, horizontal tunnels Less spoils Leaves more resource behind More expensive More dangerous Processing Remove metals by heat or chemical treatment Heat—smelting Air & water pollution--sulfur Chemical—heap-leach Piles of crushed rock sprayed with cyanide Recycling Cheaper than mining for some minerals Minimills—recycle iron and steel Substitution—new materials Environmental Impacts of Nonrenewable Mineral Resources Supplies of Mineral Resources Earthquakes Tsunamis Volcanoes Mass wasting Landslides Slumps mudslides Geological Hazards