Chapter 25 The Geology of the Cenozoic Era

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Chapter 25The Geology of the Cenozoic Era
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Introduction

• The Cenozoic began 65 mya and continues until the
  present
• Cenozoic rocks are more easily accessible and
  less deformed than older rocks
• divided into the Tertiary and Quaternary

Charles LyellTertiary, Quaternary fossils
France Eocene, Miocene, Pliocene, Pleistocene,
Holocene Paleocene and Oligocene added
later Paleogene, Neogene
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Geologic Events Cenozoic
Rockies
Mantle upwelling Colorado Plateau
Washington
Laramide uplifts eroded away
(Longest Tertiary Epoch)
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• Cenozoic Orogenic activity concentrated in two
  areas
• Alpine-Himalayan belt deformation began in the
  Mesozoic and remains geologically active.
• Isolation of Tethys to form the modern
  Mediterranean Sea
• circum-Pacific belt deformation occurred
  throughout the Cenozoic

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Cenozoic Pacific realm

• Subduction of the Farallon Plate and its Mid
  Ocean Ridge
• 2. Formation of Andean Cordillera

San Andreas forms
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Cordillera

• Circum-Pacific Orogenic belt
• Laramide Lt. Jur - E Tertiary
• further inland than most - CLUE
• deformation was vertical uplift, with little
  volcanism
• shallow subduction angle
• buoyant subduction

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Uplift of the Rocky Mountains
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Teton Range Laramide uplifts eroded away in
Oligocene, renewed uplifts Late Mio Pleist.
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Geologic Events Cenozoic
Rockies
Mantle upwelling Colorado Plateau
Washington
San Andreas Fault, Basin Range
Laramide uplifts eroded away
(Longest Tertiary Epoch)
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San Andreas transform
Ridges Change Orientation
15 mya SAF forms
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Basin and Range of Cordillera
Columbia River Basalts
Basin and Range Crust very thin there
Beginning in the Miocene, the pull of San Andreas
fault, or the Farallon Plate breaking up at
depth, causes upwelling of hot mantle rock that
stretches the overlying crust
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Basin and Range province
Extensional Feature w/ Normal Faults
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The Interior Lowlands

• Sediments eroded from the Laramide highlands were
  deposited in the Cannonball Sea Early Paleocene
• south to North Dakota.
• Terrestrial deposits are also found, but much of
  this area was experiencing erosion
• Igneous activity was significant in some areas -
  New Mexico, Colorado, Wyoming, and others
• East of the Great Plains, deposits other than
  glacial are rare until reach the Coastal Plain

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The Gulf Coastal Plain

• The Tejas epeiric sea transgressed briefly over
  the Atlantic and Gulf coastal plains E. Tertiary
• eight minor transgressive-regressive sequences
  are recognized as sea level fell in general
  reduced rifting

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East Coast

• Passive margin sedimentation dominates
• rocks form a seaward thickening wedge that dips
  gently seaward
• Cenozoic uplift and erosion produced the present
  topography of the Appalachians
• Coastal Plain Clastic Wedge
• Florida Carbonates Pliocene - Recent

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Eastern North America
Allegheny Orogeny still high
Erosion due Transgression
Coastal Plain streams and marshes
Appalachians rejuvenated recently, probably
rebound
(Water Gap)
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1.Alpine Orogen
2. Eocene to Miocene
Apennine Balkan Carpathian Caucasus Pyrenees Atlas
4.Closing of the Tethys Sea
3. Vocabulary Nappe Large recumbent folds in
thrust-fault zones where orogenic belts impinge
craton margins Flysch alternating thin shales
and sandstones. Sandstones turbidites prior
orogenic collision. Molasse non-marine deposits
accompanying the uplift of a mountain belt.
Isolation of the Mediterranean Basin Evaporites
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Nappe-folded mountains
http//www-sst.unil.ch/research/seismic/W_Alps_fil
es/zoom/W3_Inter.gif
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New Orogen, Nappes still visible
http//www.geol-alp.com/chartreuse/3_tecto_chartre
use/1_ch_occ.html
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Arabian-African Rift
1. The underside of Europe collided with numerous
microplates rifted from Africa Closing of the
Tethys Sea between late Mesozoic and early
Cenozoic time 4. Thrusts not Subduction
3. Messinian Salinity Crisis 5.5 mya
2. Pliocene three way rift. 3. Arabia
Microcontinent collision -gt Zagros Mts
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Himalayan Orogeny
Thin-skinned tectonics!
Subduction and TST
Partly subducted so under AW
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Himalayan Orogeny
AW
FAB
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Cenozoic Climates, Currents, and Volcanism

• Ocean current flow changes due to tectonics in
  Antarctic-Australian and Central American regions
• Dramatic changes in climate
• Major plume under North America
• Continuous cooling, culminating in
• on-going Ice Age

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Cenozoic Cooling
Central America construction Starts see Monterey
Fm.
Australia separates
(Northern Hemisphere)
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Geologic Events Cenozoic
Panama Closes
Mediterranean Dries Out
Circumpolar Current Antarctica
(Longest Tertiary Epoch)
High CO2
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Antarctic Circumpolar Current
Paleocene to Mid-Eocene
WARM Currents from Tropics
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Early Eocene Warm Green River Formation
Oil Shales
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Green River Formation
Lake (lacustrine) silts
Organic-rich (oil) shales w/ fossils
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Green River Formation
Tropical Plants to High Latitudes
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Antarctic Circumpolar Current
2. Late Eocene Sudden Antarctic cooling as warm
currents barred
3.
5. Longest continuous Ice Sheets
4. Fauna changes. Example Penguin
relationships from S. American bird following
current rich in fish.
1. Australia pulls away
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Fossils in volcanic tuff deposit
Cooler
Tree stumps, insects in Oligocene Ash,
Florissant, Colorado
Extensive Volcanism Late Eocene to Oligocene
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Pre Gulf Stream Current
Isthmus of Panama open, same salinity Atlantic
and Pacific
Early Pliocene
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Modern Gulf Stream Current
1. Terranes, Subduction, Volcanic Arc, Isthmus of
Panama closed, North Atlantic isol., higher
salinity, dense cool water sinks before it
reaches Arctic, polar sea freezes
Late Pliocene
2. Caused Formation of the present Gulf Stream
Current in the Atlantic 3. Dramatic Cooling
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Miocene to Pliocene Monterey Formation
17.5 to 6 MYA, documents climate changes as
Isthmus of Panama closes. Upper part Oil-rich
Cherts and diatomites, fossil whales and dolphins
and kelp which indicate modern cold currents and
rising deepwater nutrients established By 3.5 mya
Central America is complete.
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Geologic Events Cenozoic
Rockies
Mantle upwelling Colorado Plateau
Washington
Laramide uplifts eroded away
(Longest Tertiary Epoch)
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Pliocene 2000 m uplift of Colorado Plateau
(Grand Canyon - Colorado River incised )
Evidence, Incised meanders
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The Yellowstone Plume

• Miocene to Recent
• Starts with flood basalts in Columbia Plateau
  Washington and Oregon 15 mya
• Continues into Snake River Basin
• Then to Yellowstone in Holocene

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Basalt flows - Columbia Plateau
Miocene 15 12 mya Start of Plume forming Snake
River Plateau and recently Yellowstone
Just like the Watchungs
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Craters of the Moon Monument
Migration of Snake River Basin over the plume 10
mya
Migration of Yellowstone Park over the plume 2
mya to recent
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Geologic Events Cenozoic
(Longest Tertiary Epoch)
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Pleistocene Glaciation

• The Pleistocene began about 1.8 1.6 mya and
  ended about 10,000 years ago
• several intervals of widespread glaciation took
  place, separated by warmer intervals

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The Effects of Glaciation

• The effects of glacial erosion and deposition are
  evident worldwide
• lowering of sea level affected base level of
  streams
• pluvial lakes
• proglacial lakes
• Compression of the Crust

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Louis Agassiz

• Swiss Geologist
• Eventually Professor of Geology at Harvard
• Familiar with Alpine Glaciers
• Recognized Moraines, erratic boulders, and
  scoured bedrock in Europe and N.Am
• Proposed huge glaciations Europe and N. America

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Glacial and Interglacial Stages
C-14 works here Medieval warm 900-1300 Little Ice
Age 1300 -1850
65 (ongoing)
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140
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135
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(Many)
Glacial advances named for states
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Foraminifera tests - Ice Age
Warm
Cold
Wisconsinan
Illinoian
About 30 pulses in 4 or so major groups
Kansan
Nebraskan
3. Also spiral direction diversity depends on
Temp.
1. Evap. water and CO2
removes 16O from oceans 18O left in oceans
used to make shells
2. Ice traps CO2 and water with light oxygen
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Pleistocene Lakes - West
Pluvial Lakes
Remnant of Bonneville
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Lake Bonneville terraces
Much deeper that GSL
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Life of the Tertiary Period

• Angiosperms continue to dominate land plant
  communities
• Present-day groups of birds evolved
• Marine invertebrates diversify to todays fauna
• Mammals rapidly diversify
• Epochs based on similarity to Recent, not always
  extinction
• So many taxa in multiple epochs

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Marine Invertebrates and Phytoplankton

• Coccolithophores, diatoms, and dinoflagellates
  recover from K-T
• Foraminifera diversify
• Corals become dominant reef-builders
• Bivalves and gastropods are two major groups
• Echinoids evolve new forms and diversify

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Mammals

• Mammals evolve Late Triassic
• Dinosaurs extinct end of Cretaceous
• Mammals begin increasing size.
• Rapid diversification in Paleocene.
• Modern orders recognizable

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The Age of Mammals

• Four groups survive the K\T boundary
• Multituberculates extinct in Paleocene
• Monotremes lay eggs, always rare
• Marsupials young born early
• A few successful if no direct placental compet.
• Placentals

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Paleocene began 65 mya
Vast number of different forms to fill vacant
niches. Many early mammal "designs" of this time
would soon become extinct Variety of birds, other
animals, and plants increased Reptiles turtles,
crocodiles, lizards, and snakes.
Ptilodus

Diatryma U Paleocene Mid Eocene
http//www2.nature.nps.gov/geology//parks/paleocen
e.htm
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Eocene
(56 - 37 million years ago)

• Mammals the dominant land animals.
• Earliest giant forms of mammals
• Many forest plants, freshwater fish,
• and insects that were much like those today.

Diatryma
http//www2.nature.nps.gov/geology//parks/eocene.h
tm
The first horse-like creatures lived in Eocene
forests. They were barely bigger than today's
domestic cat. Throughout the Cenozoic Era their
size increased their legs became longer and
their feet changed from many-toed to
single-hoofed, for faster running. Their teeth
changed from browsing to grazing.
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Oligocene ( 37-23 million years ago)

• The climate became cooler and drier.
• More temperate forests, soft grasses
• Late Oligocene, savannas (grasslands woodlands)
• Some mammals become grazers.
• Modern groups (dogs, cats, horses, pigs, camels,
  and rodents) rose to new prominence.

http//www.prehistory.com/bronto.htm http//www2.n
ature.nps.gov/geology//parks/pliocene.htm

BRONTOTHERIUM
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Miocene (began 24 million years ago)

• Abundance of mammals peak in Miocene.
• Forests and savannas persisted in some parts of
  North America
• treeless plains expanded where cool, dry
  conditions prevailed.
• Many mammals adapted for prairie grazers,
  runners, and burrowers.
• Large and small carnivores evolved to prey on
  these plains-dwellers.
• Great intercontinental migrations occurred
  throughout the Miocene
• Animals entering and leaving North America.

Silica Grasses! High-crown teeth
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The Great Exchange

• Bears
• Camels
• Cats
• Dogs
• Elephants
• Horses
• Peccaries
• Rabbits
• Raccoons
• Skunks
• Tapirs
• Weasels

North America
Anteaters Armadillos Capybaras Glyptodonts Monkeys
Opossums Porcupines Sloths Toxodonts
South America
Late Pliocene, Isthmus of Panama closed,
migrations North and South
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Convergent EvolutionMarsupials and Placentals

• Kangaroos Antelopes
• Wallabies Rabbits
• Wombats Marmots
• Phalangers Squirrels
• Koala Sloths
• Moles Moles
• Numbats Anteaters
• Tasmanian Devil Wolverine
• Marsupial Lion Large Cats
• Tasmanian Wolf Large Canids
• Mice Mice

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Pliocene (began 5.3 million years ago)

• Most life-forms recognizable today.
• Dry open grassland environments spread
• Cooler, ever drier climate.
• Horses and other hoofed mammals
• Powerful predators

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Family tree of the horses
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Pleistocene (began about 1.6 mya)

• Glaciers covered much of North America,
• Started with widespread migrations of mammals
• Ended with massive extinctions.
• Oldest record of human occupation in North
  America is around 12,000 years ago.
• Human beings have had a profound effect on its
  animals and plants.
• Mammals recognizable

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Primate Evolution

• Several trends in the evolution of the Primate
  order help to define them
• changes in skeleton and mode of locomotion
• increase in brain size - color vision
• shift toward smaller, fewer, and less specialized
  teeth
• evolution of stereoscopic vision
• grasping hand with opposable thumb
• Homonoids diverge from Old World monkeys prior to
  the Miocene in Africa

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Earliest primate?
Squirrel-like primate Purgatorius From the
Paleocene
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Apes - Dryopithecus from Rusinga
(lived in forests)
Miocene
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Grassland SpecialistsAustralopithecus, and Us

• As we saw earlier, the ongoing completion of
  Central America had a profound influence on
  currents that the Earths climate cooled.
• The cooler drier climate caused the spread of
  grasses from temperate to some tropical regions.
  The African plains were born.
• New grassland primates evolved from the apes
• Their specialties? Upright walking, and speech.

See over the tall grass, communicate, effective
hunters
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Erect posture humans vs. gorillas
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Preview Hominids

• Hominids are bipedal, show a trend toward a large
  brain, reduced face and canine teeth, and are
  omnivores
• five species of Australopithecines are recognized
• A. anamensis ( A. afarensis Lucy) is a 4.2 mya
  bipedal species from Kenya
• earliest member Homo, H. habilis, lived 2.5 to
  1.6 mya.
• Modern Humans Cro-Magnons H. sapiens Israel
  100000 ya, later art in caves in France, Tall,
  gracile, adapted to warm regions? Contemporaneous
  with
• Neanderthals, cold specialists?
• Robust, short, nose, cerebellum

Lascaux
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Human ancestors
(Lucy - Kenyanthropus)
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Kenyanthropus
http//www.kenyanthropus.com/
Dr. Maeve Leakey
KNM1470
Kenyanthropus
Lomekwi in Kenya
http//wise.fau.edu/ctbrown/Midtermnotes.rtf
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Shanidar 1 Neanderthal skull from Iraq (50,000
years old)
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Neanderthal
Atlatl
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First Cro-Magnon dates from Israel 150000 ya
Pictured is a much later burial ritual in early
H. sapiens at Sungir, Russia, around 28,000 years
ago A 60 year old buried with an elaborate
collection of beads, necklaces and bracelets.
Notion of afterlife
WP
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The earliest work of art?
Horse carved in mammoth ivory Germany 32,000
years old