Geology 101Geology 101David BrownDavid Brown

James Hutton (1726-1797 James Hutton (1726-1797 CE)CE)

Scottish geologistScottish geologist Developed the laws Developed the laws

of geologyof geology Considered the Considered the

Father of Modern Father of Modern GeologyGeology

UniformitarianismUniformitarianism ““the present is the key to the past".the present is the key to the past". The processes (plate tectonics, mountain The processes (plate tectonics, mountain

building, erosion) we see today are building, erosion) we see today are believed to have been occurring since the believed to have been occurring since the Earth was formed. Earth was formed. http://my.hrw.com/sh2/sh07_10/student/flash/visual_concepts/80063.htmhttp://my.hrw.com/sh2/sh07_10/student/flash/visual_concepts/80063.htm

Uniformitarianism and Catastrophism

Chapter 6 Section 1 Earth’s Story and Those Who First Listened

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Visual Concept

Law of Original HorizontalityLaw of Original Horizontality Sedimentary rocks are laid down in Sedimentary rocks are laid down in

horizontal or nearly horizontal layers.horizontal or nearly horizontal layers.

Law of SuperpositionLaw of Superposition In an undisturbed rock sequence, the In an undisturbed rock sequence, the

bottom layer of rock is older than the layer bottom layer of rock is older than the layer above it.above it.

http://my.hrw.com/sh2/sh07_10/student/flash/visual_concepts/80065.htmhttp://my.hrw.com/sh2/sh07_10/student/flash/visual_concepts/80065.htm

Cross Cutting RelationshipsCross Cutting Relationships The thing doing the cutting is younger The thing doing the cutting is younger

than the rock being cut.than the rock being cut.

InclusionsInclusions The included rock is older than the rock The included rock is older than the rock

around it.around it.

Law of Faunal SuccessionLaw of Faunal Succession Fossils occur in a definite, invariable Fossils occur in a definite, invariable

sequence in the geologic record. sequence in the geologic record. Index fossils help determine age of rock.Index fossils help determine age of rock.

UnconformityUnconformity Gaps in the rock record caused by Gaps in the rock record caused by

weathering, erosion, and volcanic action.weathering, erosion, and volcanic action.

Unconformities

Chapter 6 Section 2 Relative Dating: Which Came First?

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Visual Concept

CorrelationCorrelation The matching of The matching of

rock outcrops of rock outcrops of one region to those one region to those of another region.of another region.

Geologists use Geologists use fossils, unique fossils, unique rocks, or mineral rocks, or mineral features to match features to match the layers.the layers.

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Geologic Column

Chapter 6 Section 2 Relative Dating: Which Came First?

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Visual Concept