Principles of Historical Geology II

Historical Geology – Principles II

Unconformity:

a surface between layers of rock

which formed during a

time of erosion or non-deposition

Historical Geology – Principles II

An unconformity:

represents “missing time”

(time without as sedimentary record)

Historical Geology – Principles II

Monday, April 23rd

Construction rained out for 3 weeks

(non-deposition)

Monday, April 23rd

Monday, April 23rd

Wednesday, June 1st

disconformity

1980

1980

30 yrs later: the wall is

demolished, but a foundation

kept for a new wall.

“erosion”

1980

2010disconformity

30 missing yrs

sedimentary rocks

sedimentary rocks

parallel to

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Sedimentary

Sedimentary

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erosion

erosion

Sedimentary

Sedimentary

Grand Canyon

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Devonian Sedimentary

Mississippian Sedimentary

Erosion Surface

sedimentary rocks

non - sedimentary rocks

on

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Proterozoic Metamorphic

Cambrian Sedimentary

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Cranberry Gneiss1.1 billion yrs old

Unconsolidatedstream gravel1.1 billion yrs old

Nonconformity

Boone CreekRivers St & Varsity Gym

sedimentary rocks

sedimentary rocks

over tilted

Sedimentary

Sedimentary

More Principles

Charles Lyell: Text Book (early 1800's)

"Principles of Geology"

A uniformitarian "how to" book

a classic still in print

Historical Geology – Principles II

More Principles

Inclusion of Components: A body of rock is younger than

a second body from which any

of its pieces are derived.

Historical Geology – Principles II

More Principles

Inclusion of Components:

Le

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Historical Geology – Principles II

More Principles

Crosscutting Relationships:

Features are younger than the rocks that they transect,

and younger than any other feature they transect.

Historical Geology – Principles II

More Principles

Crosscutting Relationships:faults, igneous intrusions, unconformities

Historical Geology – Principles II

More Principles

Historical Geology – Principles II

Crosscutting Relationships:

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Three Major Rock Types

Igneous:

Metamorphic:

Sedimentary:

Historical Geology – Principles II

Rock Cycle

Review

If you don’t remember the differencebetween a gneiss & a graniteor a slate and a shale...

Review Chapter 2Review specimens in Geology Museum

Historical Geology – Principles II

Unifying Theory

Chemistry: atomic theory

Physics: Newtonian/quantum/unified theory

Biology: evolution - natural selection

Geology: ?

Historical Geology – Principles II

Unifying Theory

Geology: Plate Tectonics

• 1960’s

• community effort

(atypical paradigm shift)

Historical Geology – Principles II

Plate Tectonics: unifying theory of geology

Earth as a System

Earth as a System

Historical Geology – Principles II

Inter-related processes:

• physical

• chemical

• biological

Earth as a System

Historical Geology – Principles II

Inter-related processes:

• physical

• chemical

• biological

Some of themcyclic

Plate tectonics

Water cycle

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Great Barrier Reef