GEOLOGICAL MARVELS: The Colorado Plateau and the SC 204 January 9, 2013

Gil Brenner John Bush Gary Oberts

RIO GRANDE RIVER WEST OF TAOS NEW MEXICO RIO GRANDE RIVER ISLETA PUEBLO-NEAR ALBUQUERQUE RIO GRANDE RIFT WEST OF GRANTS NEW MEXICO

CONTINENTAL DIVIDE CENTRAL COLORADO

CONTINENTAL DIVIDE I-40 WESTERN NEW MEXICO

CONTINENTAL DIVIDE I-40 WESTERN NEW MEXICO RED ROCK STATE PARK NEAR GALLUP NEW MEXICO

PETRIFIED FOREST NEAR HOLBROOK PETRIFIED FOREST NEAR HOLBROOK ARIZONA NEAR WINSLOW ARIZONA BARRINGER CRATER NEAR FLAGSTAFF ARIZONA BARRINGER CRATER

SAN FRANCISCO MOUNTAINS NEAR FLAGSTAFF ARIZONA SAN FRANCISCO MOUNTAINS FLAGSTAFF ARIZONA SAN FRANCISCO VOLCANIC FIELD SEDONA ARIZONA COCONINO PLATEAU WEST OF SELIGMAN ARIZONA HURRICANE FAULT EAST OF KINGMAN ARIZONA NEAR NEEDLES CALIFORNIA

GRAND CANYON FROM NAVAJO POINT

LAKE POWELL GLEN CANYON DAM LEE’S FERRY/NAVAJO BRIDGE MARBLE CANYON BELOW LEE’S FERRY PEARCE FERRY RAPID

LAKE MEAD HOOVER DAM HELICOPTER TOUR OF GRAND CANYON Geologic Time Scale GRAND CANYON GRAND CANYON PRECAMBRIAN GEOLOGIC COLUMN • Elves Chasm Pluton (gneisses) 1840 Ma • Granite Gorge Metamorphic Suite 1750- 1730 Ma – Rama & Brahma Metavolcanics – Vishnu Schist Metasediments – Zoroaster Granite • The “Greatest Unconformity” 480 myrs • 1250 Ma- 750 Ma – LS, SH, SS – Nankoweap Formation SS, MS – DO, LS, SH, SS – BR, SS • The 200 myrs

GRAND CANYON GRAND CANYON SUPERGROUP TONTO PLATFORM TAPEATS SS, BRIGHT ANGEL SH, MUAV LS KAIBAB LIMESTONE

UINKARET VOLCANIC FIELD GEOLOGIC MAP OF GRAND CANYON USGS G. H. BILLINGSLEY 2000

HERITAGE SQUARE FLAGSTAFF ARIZONA

PALEOGEOGRAPHIC MAPS

Ron Blakey Colorado Plateau Geosystems, Inc PRESENT PRESENT Geologic Time Scale LATE CAMBRIAN (500 Ma)

Iapetus Ocean Greenland

Panthalassa Ocean

North America GRAND CANYON PRECAMBRIAN GEOLOGIC COLUMN • Elves Chasm Pluton (gneisses) 1840 Ma • Granite Gorge Metamorphic Suite 1750- 1730 Ma – Rama & Brahma Metavolcanics – Vishnu Schist Metasediments – Zoroaster Granite • The “Greatest Unconformity” 480 myrs • Grand Canyon Supergroup 1250 Ma- 750 Ma – Unkar Group LS, SH, SS, LA – Nankoweap Formation SS, MS – Chuar Group DO, LS, SH, SS – Sixtymile Formation BR, SS • The Great Unconformity 200 myrs

EARLY CAMBRIAN 525 Ma

Tonto Group Tapeats SS Bright Angel SH Muav LS Geologic Time Scale MID MISSISSIPPIAN (340 Ma)

Arctica Baltica North Slope Greenland Panthalassa Ocean Laurussia

North America Africa

Florida Yucatan Hunic terrane Gondwana South America MID MISSISSIPPIAN 340 MA

Temple Butte Fm (D) DO Redwall Limestone LS Surprise Canyon Fm CO SS LS MS Geologic Time Scale LATE PENNSYLVANIAN (300 Ma) Baltica North Slope Greenland Panthalassa Ocean

North America Africa

Yucatan Florida

Hunic terrane Gondwana South America LATE PENNSYLVANIAN 304 Ma

Supai Group Watahomigi Fm LS MS DO Manakacha Fm SS MS Wescogame Fm SS

Geologic Time Scale EARLY PERMIAN (280 Ma)

Baltica North Slope Greenland Panthalassa Ocean

North America Africa

Yucatan Florida Gondwana

Hunic terrane South America 295 Ma EARLY PERMIAN

Esplanade Sandstone SS Hermit Fm MS SS Coconino Sandstone SS Toroweap Fm East SS West GY DO LS SS MID PERMIAN 270 Ma

Kaibab Fm -Fossil Mountain West LS East LS SS -Harrisburg GY SS MS LS

Geologic Time Scale THAT’S ALL THAT SURVIVES* BUT ELSEWHERE ON THE PLATEAU

• There are places where rocks date from 250 Ma to Recent • At Grand Canyon weathering and erosion has stripped away the rest— “unroofing” – When did unroofing happen? – How did unroofing happen? – How much rock was removed? – Where did all that rock go? *Except for some lava flows

FOCAL QUESTIONS FOR THIS CLASS

• GRAND CANYON – WHEN WAS IT FORMED? – HOW WAS IT FORMED? • COLORADO PLATEAU – WHAT LIFTED IT? – WHEN WAS IT LIFTED? – WHAT HOLDS IT UP? THESE ARE CONTROVERSIAL TOPICS • Answering them requires integrating loosely connected technical specialities – Sedimentary geology – Igneous geology – Tectonics – Geomorphology-weathering, erosion, deposition – Life sciences- ichthyology, botany, genetics – Atmospheric sciences-climatology • The facts keep growing as new techniques are devised and the theories keep changing partially as a consequence