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Structure of the Earth and the Rock Cycle. Lithosphere composed of minerals Definition of “Mineral” ? Definition of “Mineral” ?

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Presentation on theme: "Structure of the Earth and the Rock Cycle. Lithosphere composed of minerals Definition of “Mineral” ? Definition of “Mineral” ?"— Presentation transcript:

1 Structure of the Earth and the Rock Cycle

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3 Lithosphere composed of minerals Definition of “Mineral” ? Definition of “Mineral” ?

4 Silicate minerals 92% of crust 92% of crust silicon and oxygen silicon and oxygen

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

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

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

9 Basalt with vesicles

10 extrusive

11 intrusive

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

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

14 mudstone

15 sandstone

16 limestone

17 conglomerate

18 strata

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

24 gneiss schist

25 slate

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27 Rock Cycle

28 Structure of Earth

29 Core Core Mantle Mantle Crust Crust

30 Core Inner Inner 5150 – 6370 km (below surface) 5150 – 6370 km (below surface) Solid iron Solid iron 5400 – 9000 degrees F 5400 – 9000 degrees F Outer Outer 2900 – 5150 km 2900 – 5150 km Molten iron Molten iron

31 Core Core Mantle Mantle Crust Crust

32 Lower mantle Lower mantle Upper Upper Uppermost Uppermost

33 Lower mantle Lower mantle very dense; iron and magnesium very dense; iron and magnesium 670 – 2900 km 670 – 2900 km Upper mantle Upper mantle rigid at lower end rigid at lower end “plastic” toward crust: asthenosphere “plastic” toward crust: asthenosphere km km Uppermost mantle Uppermost mantle Rigid Rigid “Moho” to 70 km “Moho” to 70 km

34 “Moho” “Moho” Mohorovičić discontinuity Mohorovičić discontinuity Boundary between crust and mantle Boundary between crust and mantle Change in seismic waves here Change in seismic waves here

35 Core Core Mantle Mantle Crust Crust

36 continental : 25 miles thick continental : 25 miles thick Lower mafic; upper felsic (granite) Lower mafic; upper felsic (granite) Less dense Less dense oceanic: 5-6 miles thick oceanic: 5-6 miles thick Mafic (basalt) Mafic (basalt) More dense More dense Lithosphere = uppermost mantle and crust Lithosphere = uppermost mantle and crust Rigid Rigid ultramafic ultramafic

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39 Lithosphere is divided into large plates Lithosphere is divided into large plates rigid plates “float” on the plastic asthenosphere, just deep enough to support their own weight: rigid plates “float” on the plastic asthenosphere, just deep enough to support their own weight: Isostasy Isostasy

40 Isostatic adjustment of crust: Isostatic adjustment of crust: add weight (sediment, glacial ice): crust will sink add weight (sediment, glacial ice): crust will sink remove weight (erosion, glacial ice melts): crust will rebound remove weight (erosion, glacial ice melts): crust will rebound

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44 ice Crust sank Crust rebound Duluth Northeast “drowned “ St. Louis River


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