Transcript No Slide Title

HISTORICAL GEOLOGY
EARLY CENOZOIC I.
EARLY CENOZOIC:
(65-1.8 MYBP):
Introduction: Much of
the landscape as it
appears today resulted
from a number of
"land-forming" events
of the early Cenozoic.
Harry Williams, Historical Geology
1
Paleogene
Paleogeography.
Harry Williams, Historical Geology
2
Appalachians and
Coastal Plains
Rockies and Great Plains
Harry Williams, Historical Geology
3
Gulf Coast Main area of marine transgressions and regressions
during Cenozoic, this, combined with pronounced subsidence,
resulted in about 10 000 m of Paleogene/Neogene sediments
underlying the Gulf Coast
Harry Williams, Historical Geology
4
East Coast
Relatively quite
during the Cenozoic. The
erosion of the Appalachians
continued, producing
subdued, rounded mountains
(characteristic of ancient
mountains). The coastal plain
and continental shelf
continued to be built from
clastics in the northeast and
carbonates in the southeast
(Florida).
Harry Williams, Historical Geology
5
Low, rounded,
vegetated
mountain ridges
in the
Appalachians.
Harry Williams, Historical Geology
6
East coast coastal
plain – dominated by
coastal processes and
landforms e.g. spits,
barriers, beaches,
marshes, etc.
Cape
Fear
Harry Williams, Historical Geology
7
Barrier Island
Mississippi delta
Harry Williams, Historical Geology
8
Bahama Banks
Harry Williams, Historical Geology
9
Rockies Continuing uplift and erosion shaped the Rockies into
rugged, sharp peaks (characteristic of youthful mountains). In some
areas, large fault blocks were pushed up to form mountain ranges,
such as the Tetons of Wyoming. Clastics from the erosion spread
eastward, forming the Great Plains.
Tetons.
Harry Williams, Historical Geology
10
West Coast Tectonics
Subduction down much of the
west coast stopped in the
Cenozoic, as the Farallon
Plate* and the east Pacific
Rise were “swallowed” by the
subduction zone. Instead, a
transform fault developed
about 10 million years ago.
Subduction continued to the
north (Juan de Fuca plate)
and the south (Cocos plate). A
number of features are related
to these plate movements…
* 1st time we’ve covered the
Farallon Plate.
Harry Williams, Historical Geology
11
San Andreas Fault
Cascades
Columbia Plateau
Basin and Range
Colorado Plateau
Harry Williams, Historical Geology
12
San Andreas Fault
Harry Williams, Historical Geology
13
Mt. St. Helens, 1980.
The Cascades - volcanic arc.
Harry Williams, Historical Geology
14
Columbia Plateau - flood
basalts resulting from a
hot spot.
Harry Williams, Historical Geology
15
Basin And Range Province Tensional forces developed in large
areas of Nevada, Arizona, New Mexico and South California
during the Cenozoic, probably resulting from the change from
subduction to transform fault along the craton margin and heat
flow from subduction. The result was basin and range topography,
characterized by normal faults, tilted fault blocks, grabens and
horsts:
Harry Williams, Historical Geology
16
Range
Basin
Death Valley, California.
Harry Williams, Historical Geology
17
Graben and horst.
Harry Williams, Historical Geology
18
Tilted fault blocks.
Harry Williams, Historical Geology
19
Colorado Plateau
A large block of crust in
the southwest remained
relatively undeformed, but
was uplifted during the
Cenozoic (5 -10 mybp),
forming the Colorado
Plateau. Streams cut down
into the plateau as it was
lifted up, forming deep
canyons, including the
Grand Canyon (2600 m
deep). Magma was
released from faults
surrounding the uplifted
plateau.
Harry Williams, Historical Geology
20
Grand Canyon.
Harry Williams, Historical Geology
21
Plateaus, mesas, buttes and pinnacles formed by stream erosion of
uplifted strata.
Harry Williams, Historical Geology
22
Tethys Seaway
Closure of the Tethys Seaway was completed during the
Cenozoic. Africa collided with Europe about 40 million years
ago forming the PYRENEES, between France and Spain, and
the ATLAS MOUNTAINS of northwest Africa. As Africa swung
around, the collision spread eastward, forming the ALPS of
southern Europe. Areas of the Alps are still undergoing periodic
uplift today (the collision continues). Further east, India
collided with Asia about 10 million years ago, forming the
HIMALAYAS (the top of Mt. Everest is marine limestone);
these mountains are also continuing to rise – frequent
earthquakes in India/China attest to the continuing movement.
These orogenies created a long linear zone of mountains
running east – west across Europe and Asia.
Harry Williams, Historical Geology
23
Harry Williams, Historical Geology
24
Harry Williams, Historical Geology
25