100 t07 cycle - university of...

Chapter 3 Patterns in Nature:

Minerals

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Essentials of Geology, 4th edition by Stephen Marshak © 2013 W.W. Norton & Company

PowerPoint slides prepared by Rick Oches, Professor of Geology & Environmental Sciences, Bentley University, Waltham, Massachusetts

By Stephen Altaner (Univ. of Illinois)

GEOL 100 (Planet Earth) Topic #7 - The Rock Cycle

Essentials of Geology, 4th edition, by Stephen Marshak © 2013, W. W. Norton ! Chapter 3: Patterns in Nature: Minerals!

Rock Definition Rock = coherent, relatively hard, naturally formed mass of mineral matter


Importance of Rocks •  Natural Hazards - Volcanoes, sinkholes, landslides

are directly linked to rock


Importance of Rocks •  Natural Hazards - Damage from floods, earthquakes

is related to bedrock type


Importance of Rocks •  Natural Resources - Rock

US Production of Crushed Stone, Sand, Gravel - Projected to 2020


Importance of Rocks •  Natural Resources - energy (oil, coal, natural gas)


Minerals

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Importance of Rocks •  Natural Resources - Groundwater


Importance of Rocks •  Natural Resources - Groundwater


Importance of Rocks •  Geologic History


Rock Characterization Rocks are characterized based on: 1) Mineral content 2) Texture - size (large = coarse-grained; small, microscopic =

fine-grained), shape, arrangement of mineral grains (aligned or random).


Classes of Rocks - Igneous Form by cooling and solidification of hot molten rock, which can cool at Earth's surface (extrusive igneous rock) or below Earth's surface (intrusive igneous rock)


Classes of Rocks - Igneous Typical texture = interlocking with random arrangement, no space between grains similar to jigsaw puzzle


Minerals

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Classes of Rocks - Sedimentary Most form by hardening (lithification) of layers of sediment (loose grains of preexisting rock) deposited at Earth's surface. Typical feature = layering, horizontal bands formed by settling of grains in water (or land)


Classes of Rocks - Sedimentary Typical texture = compacted or cemented (grains compressed together with or without mineral cement).


Classes of Rocks - Metamorphic Form when preexisting rock changes (shape or mineral content) due to intense heat and pressure; usually occurs deep below Earth's surface (e.g., during mountain building). Typical texture = foliated (and interlocking), metamorphic banding.


Rock Cycle Depicts where and how three rock classes form and how they are related to each other


Rock Cycle Each rock class forms from preexisting rock (constantly recycled), sedimentary rocks form near Earth's surface, metamorphic rocks form at great depths, molten rock occurs at various depths, forming igneous rock when it cools


Rock Cycle Cycle is driven by burial, which sends rock deeper underground and uplift, which brings rock back to surface; Can be interrupted, i.e., doesn’t have to proceed through entire cycle

100 t07 cycle - university of...

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