Parks Formed by Stream Erosion and Weathering part 1

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Parks Formed by Stream Erosion and
Weathering(part 1)

• GRAND CANYON NATIONAL PARK
• ZION NATIONAL PARK

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Colorado Plateau

• relatively undeformed rocks
• surrounded by the highly deformed Rocky
  Mountains, and Basin and Range Provinces.
• The margins of the Colorado Plateau are marked by
  major volcanic accumulations
• The major structures of the plateau include
• broad flexures,
• monoclines,
• vertical faults,
• igneous laccoliths and volcanics
• Salt tectonic features.

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• Stratigraphy of Colorado Plateau
• From Geology of the Colorado Plateau, 1999,
  Annabelle Foos, Geology Department, University of
  Akron

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Grand Canyon NP - Vital Statistics

• Northwest Arizona
• Western Colorado Plateau
• 1,200,000 acres or 1,900 square miles

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Native American History

• 1000 BC Evidence of Native American Hunters in
  caves, artifacts
• Basket Making Native Americans
• AD 1350 Pueblo culture (500 sites)
• Up to today, still home of three tribes
• Navajo (east)
• Hopi (east)
• Havasupai (west)

Photo NPS
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Human History (cont)

• 1540, Don Lopez de Cardenas
• 1869, John Wesley Powell lead expedition of 4
  wooden boats 9 men down the Colorado River
  (again in 1871)
• 1893 protected as a Forest Reserve
• 1908 TR proclaimed the area a NM
• 1919 established as Park

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Geologic Features

• Stream Erosion
• Mass Wasting
• Differential Erosion
• Unconformities

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Stream Erosion

• Colorado River is 2nd longest river in US
• Colorado River eroded Grand Canyon
• Canyon is 217 miles long, 1 mile deep, up to 18
  miles wide
• Erosion began between 5 million years ago
• PANORAMIC VIEW OF THE GRAND CANYON FROM PIMA
  POINT ON THE WEST RIM DRIVE, GRAND CANYON N.P.
  NPS PHOTO.

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Stream Erosion

• Colorado River
• Erosion mainly vertical

VIEW DOWN THE COLORADO RIVER IN GRAND CANYON N.P.
FROM NANKOWEAP IN MARBLE CANYON. MIKE QUINN, NPS
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Mass Wasting

• Movement of material downward due to gravity
• Main process involved in widening canyon
• Climate is arid mechanical weathering talus

Photo Mirsky
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Differential Erosion

• Responsible for rugged nature of cliffs
• Caused by different degree of resistance to
  erosion
• Resistant cliffs limestone, sandstone
• Less resistant slopes shales
• Unconformity Buried erosion surface

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Differential Erosion
Kaibab SS Coconino SS Hermit Sh Supai
Group Redwall Ls Bright Angel Sh Tapeats SS
Photo CD, HTT
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Unconformities PC/C nonconformity
Tapeats Sandstone
Vishnu Schist
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Unconformities PC/C angular unconf.
Tapeats Sandstone
Grand Canyon Series
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Geologic History - Stratigraphy
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Geologic History Pre-Cambrian

• 2,000 mya marine sediments and volcanic rocks
  (since metamorphosed into Vishnu Schist) and
• 1,700 mya folding, faulting, intrusions(Zoroaster
  Granite)
• 1,000 mya sea transgressed and deposited Grand
  Canyon Series
• Mountain building, then erosion to low hills

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Geologic History Paleozoic

• Cambrian Sea transgresses again
• Tapeats Sandstone
• Bright Angel Shale
• Ordovician, Silurian no rock record
• Devonian Temple Butte Limestone

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Geologic History Paleozoic

• Mississippian
• Redwall limestone - marine
• Pennsylvanian
• Supai formation lower part marineupper part
  non marine, with reptile tracks
• Permian near shore alternating
• Hermit Shale non-marine, more tracks
• Coconino sandstone dune sand, x-beds
• Toroweap formation marine
• Kaibab limestone top cliff, marine

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Geologic History Mesozoic

• Thousands of feet of sediment deposited, but
  mostly eroded away from GC area
• Rock of this age to north (Zion, Bryce), east
  (Painted Desert, Black Mesa) and remnants near
  Grand Canyon at Cedar Mt.

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Geologic History - Cenozoic

• Miocene Ancestral Colorado River flowed over
  lowlands with little elevation
• Pliocene beginning of uplift of Colorado
  Plateau (continues to present)
• Mid-Pliocene Colorado River entrenchment begins
  4-6 mya

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Geologic History Pleistocene to Today

• Colorado River cut quickly through Pz sed
• Inner Gorge cut more slowly
• River only removes material in its channel
• Mass wasting delivers sediment to river
• Faulted areas form tributary valleys

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Zion National Park
Cliffs of Navajo Sandstone
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Vital Statistics

• Southwest Utah
• Western Colorado Plateau
• 147,000 acres or 230 square miles
• 1909 Monument (by TR)
• 1919 National Park
• Expanded in 1937 1956

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Later Human History

• AD 500 Basket Maker Culture Native Americans
• Later, Piute tribe
• 1776, Don Lopez de Cardenas
• 1872, John Wesley Powell lead expedition and
  named the area Mukuntuweap
• 1909 TR proclaimed the area a NM as Mukuntuweap
  NM
• 1918 name changed to Zion NM
• 1919 established as Park

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Geologic Features

• Stream Erosion Mass Wasting
• Structural Control
• Weathering
• Arches

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Stream Erosion Mass Wasting

• Virgin River has gradient of 60 ft/mi
• Mass wasting widens Zion Canyon
• Sapping by springs creates overhangs
• Tributaries less water, left hanging

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Structural Control

• Rectangular stream pattern fractures
• Columns and Pyramids
• Vertical fractures encourage vertical cliffs
• Rapid downcutting through soft sandstone leaves
  deep, narrow canyons
• Bedding planes also act as plane of weakness

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Structural Control

• Rectangular stream pattern fractures
• Columns and Pyramids
• Vertical fractures encourage vertical cliffs
• Rapid downcutting through soft sandstone leaves
  deep, narrow canyons
• Bedding planes also act as plane of weakness

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Structural Control - Columns and Pyramids
Cliffs of Navajo Sandstone

• Rectangular stream pattern fractures
• Columns and Pyramids
• Vertical fractures encourage vertical cliffs
• Rapid downcutting through soft sandstone leaves
  deep, narrow canyons
• Bedding planes also act as plane of weakness

Great White Throne
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Structural Control

• Rectangular stream pattern fractures
• Columns and Pyramids
• Vertical fractures encourage vertical cliffs
• Rapid downcutting through soft sandstone leaves
  deep, narrow canyons
• Bedding planes also act as plane of weakness

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Structural Control - Bedding planes also act as
plane of weakness
Checkerboard Mesa Navajo Sandstone

• Rectangular stream pattern fractures
• Columns and Pyramids
• Vertical fractures encourage vertical cliffs
• Rapid downcutting through soft sandstone leaves
  deep, narrow canyons
• Bedding planes also act as plane of weakness

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Weathering

• Rock color from iron oxide
• Frost wedging
• Acid dissolves calcium carbonate cement
• Arches example Kolab Arch

Kolab Arch
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• Stratigraphy of Colorado Plateau
• From Geology of the Colorado Plateau, 1999,
  Annabelle Foos, Geology Department, University of
  Akron

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Geologic History

• Permian Kaibab limestone shallow sea
• Triassic
• arid near-shore
• Uplift and some volcanic ash
• Fossils fresh water fish, clams, snails,
  amphibians, wood, dinosaur tracks

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Geologic History Jurassic

• Navajo Sandstone arid climate with sand dunes
  (up to 2000 ft thick)
• Forms the White Cliffs
• Frosted, fine-grained, quartz sandstone
• Cross-bedded
• Capped by marine Carmel Formation

Navajo Sandstone
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Geologic History - Jurrasic
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Geologic History Cretaceous and Cenezoic

• Cretaceous (End of Mz) erosion
• Lt. Miocene (13mya) block faulting
• Tilted
• Uplifted increased river gradient, rejuvenated
  stream erosion, carved Zion Canyon