Structure of the Earth and the Rock Cycle

Structure of the Earth and the Rock Cycle

Lithosphere composed of minerals n Definition of “Mineral” ?

Formation of Rocks n Rocks are formed beneath or on the surface of the Earth.

n A rock is a natural solid substance made up of minerals n rocks classified by origin : 3 types

Types of Rocks 1. IGNEOUS n molten rock that has cooled and solidified n molten rock is magma or lava a) INTRUSIVE n cools below surface; big crystals; coarse b) EXTRUSIVE n cools at surface; fine

Fine-textured extrusive Coarse-textured intrusive Glassy; rapid cooling

Basalt with vesicles

extrusive

intrusive

Mafic and felsic igneous rock n Felsic: mostly felsic minerals n n Mafic: mostly mafic minerals n n High in feldspar and silicate minerals Lighter Less dense High in magnesium and iron Darker Denser Ultramafic: all mafic minerals

2. SEDIMENTARY n made up of sediments that have been compacted and cemented. n sediments: all solid particles transported by water, ice, wind, gravity n n n mud, sand, shells, debris, dust, rock fragments mudstone, sandstone, limestone, conglomerate, shale accumulate in strata (layers)

mudstone

sandstone

limestone

conglomerate

strata

3. METAMORPHIC n n altered from original rock by heat, pressure or chemical activity began as igneous, sedimentary, or metamorphic rock n shale --> slate n slate --> schist n granite --> gneiss n limestone --> marble

gneiss schist

slate

Rock Cycle

Structure of Earth

Earth’s Interior • Core – – dense Iron and Nickel Inner Core - solid Outer Core - liquid • Mantle – – Less dense than core Iron and Magnesium silicates Mostly solid Upper mantle is partially molten molte • Crust Outermost layer Very thin and rigid Continental – granite – Density = 2. 8 g/cm 3 – Oceanic – basalt – Density = 3. 0 g/cm 3 – – –