The Lithosphere, Rocks and minerals

Why rocks are important

1. Natural history

2. valuable raw materials

3. rock salt

Natural History

• Baraboo Quartzite at Devil’s Lake

Valuable Raw Materials

• Diamond-bearing volcanic rocks

• Kimberlite pipes

Rock Salt

• salt for ice/snow

• salt rocks contain extractable hydrocarbons

Geological Time Scale

1. Cenozoic

2. Mesozoic

3. Paleozoic

4. Precambrian

Oldest Earth MIneral

Zircon crystal (4.4 by old)

Oldest Rock

Gneiss (4.03 by old)

Oldest Evidence of Life

microbial imprint (3.5 by old)

Oldest Rock in the U.S.

gneiss in Wisconsin (2.8 by old)

Precambrian

• 540 mya - 4.54 bya

• first rocks formed

• bacteria and prokaryotes

• oxygenation of atmosphere

Paleozoic

• 245 mya - 540 mya

• plants colonized land

• Cambrian explosion (Trilobite)

• first vertebrates

• first land plant

• first insects

• first land vertebrates

• coal swamps

Mesozoic

• 65 mya - 245 mya

• appearance and extinction of dinosaurs

• first birds

• first flowers

Cenozoic

• last 65 my

• dominance of flower plants and mammals

• rise of humans

What is a Mineral

• solid

• naturally occurring

• inorganic

• crystalline

2 Types of Minerals

• Silicates

• Non-Silicates

Silicates

• 90% of earth crust

• mafic and felsic minerals

• clay

Non-Silicates

• 10% of earths crust

• carbonates, oxides, sulfides

Mafic and Felsic

• formed from molten rock

• basic unit of silica tetrahedron

Felsic Minerals

Lighter in density and color

Mafic Minerals

darker and denser than felsic

Feldspar

• most common group of minerals in earths crust

• composed of SoO4 and Al, plus Ca, K, Na