Transcript COASTAL PLAIN - New Jersey City University [NJCU]

COASTAL PLAIN
CRETACEOUS TO RECENT
Cretaceous History of
North America
• The Cretaceous was a time of high sea
level and vast epicontinental seas.
• The most prominent feature in North
America during the Cretaceous, was the
shallow epicontinental sea that flooded
much of the western interior of the
continent, from the Gulf of Mexico to the
Arctic Ocean, as well as the Atlantic and
Gulf Coastal Plains.
Cretaceous
Paleogeography
Cretaceous Chalk
• Chalk, a white, fine-grained variety of
limestone composed of microscopic shells
(called coccoliths) of golden-brown algae,
was deposited in many places around the
world during the Cretaceous.
• The word Cretaceous is derived from the
Latin word for chalk, creta.
Atlantic Coastal Plain
• The Atlantic Coastal Plain began to
subside (or sink) early in Cretaceous time.
• Marine and deltaic sediments
accumulated, gradually building a wedge
of sediments that thickened seaward.
• Most of the Cretaceous sediment in this
area was deposited on the present-day
continental shelf.
Atlantic Coastal Plain
Late Cretaceous Units
• POTOMAC FORMATION - (early and late
Cretaceous) - A moderately well sorted and
cross-bedded, quartz sand with quartz and
quartzite pebbles deposited in fluvial
environments.
• The Potomac Formation is the basal sequence
of the Cretaceous system in southern and
central New Jersey (it is not recognized beneath
the lower Raritan Formation in the bay area).
• The thickness is reported in the range of 250 to
800 feet.
Late Cretaceous Units
• RARITAN FORMATION - (Cenomanian, Cretaceous) - In the
Raritan Bay region the Raritan Formation unconformably
overlies Newark Basin and older rocks, representing the
beginning of a series of major transgressions and regressions
of the seas during Cretaceous time.
• The Raritan consists of clay, sand, lignite, and gravels
representing progradational alluvial plain, coastal and neashore
marine environments.
• Very well exposed in unglaciated regions around the western
end of Raritan Bay.
• Subdivided units include the Raritan Fire Clay, Farrington Sand
Member, Woodbridge Clay Member, Sayreville Sand Member,
and South Amboy Fire Clay Member (oldest to youngest,
respectively).
• The Sayerville Sand Member is famous for its amberbearing lignite lenses, insect remains, fossil wood and
leaves, and pyrite nodules.
• The Sayreville fossil beds have yielded an astonishing amount
of information about life in the Late Cretaceous.
Sayreville/Kennedy Park
Amber in the Raritan Formation
The Sayreville Clay Member of the Raritan Formation yields amber form scattered
lignite horizons. The amber is not of consistently high quality like other amber-bearing
regions of the world. However, it is one of the older amber-bearing deposits, and the
amber frequently contains insects (mostly gnat-like insects).
Late Cretaceous Units
• MAGOTHY FORMATION - (Coniacian and Santonian,
Cretaceous) - Unconformably overlies the Raritan
Formation.
• The Magothy Formation is beneath Quaternary glacial
cover throughout most of Long Island, the south shore of
Staten Island, and is fairly well exposed in small
outcrops and excavations around Raritan Bay.
• The Magothy is subdivided into units: the Oldbridge
Sand Member, the Amboy Stoneware Clay Member, and
Cliffwood Beach Member (oldest to youngest,
respectively).
• The Magothy represents nearshore and alluvial
depositional environments, similar to the Raritan
Formation.
• The thickness ranges between 10 and 200 feet.
Late Cretaceous Units
• MERCHANTVILLE FORMATION - (late
Santonian to early Campanian, Cretaceous) Conformably overlies the Magothy Formation
and consists of mixed sand and clay units
representing nearshore and shallow marine
depositional environments.
• It is poorly exposed around the southern side of
Raritan Bay.
• It interfingers with the overlying Woodbury Clay.
• The thickness of the unit measures between 20
and 100 feet.
Late Cretaceous Units
• WOODBURY SHALE - (early Campanian,
Cretaceous) - Dark gray clay mud of the
Woodbury Clay is exposed in excavations
and along the shore of Raritan Bay near
Cheesequake State Park, NJ.
• The gray carbonaceous shale contains
pyrite and bioturbation features of a
marine or lagoonal environment.
Late Cretaceous Units
• ENGLISHTOWN FORMATION - (early
Campanian, Cretaceous) - The Englishtown
consists of clay, slit and sand which locally
displays lamination, thin- to thick- bedding, and
cross stratification.
• Fossils are generally scarce. Locally the unit
contains lignite beach-type sand deposits.
• The upper-most bed display bioturbation with
burrows locally filled with glauconitic quartz sand
from the unconformable overlying Marshalltown
Formation.
• The formation ranges from 20 to 150 feet in
thickness.
Late Cretaceous Units
• MARSHALLTOWN FORMATION - (middle
Campanian, Cretaceous) - The Marshalltown
consists of greenish-gray massive quartz-rich,
glauconitic sand, silt and dark, micaceous clay.
• Pyrite and siderite concretions, some displaying
evidence of boring and reworking, are abundant
at the base of the unit.
• Other than traces of lignite and bioturbation,
fossils are scarce in the unit.
• The thickness of the formation is between 15 to
20 feet.
Late Cretaceous Units
• WENONAH FORMATION - (late Campanian,
Cretaceous) - The Wenonah consists of micaceous
quartz and silt and is rich in organic material (mostly
silt-sized lignite fragments) and pyrite (in very fresh
exposures).
• The unit ranges in thickness from 35 to 55 feet along
Raritan Bay, inland the upper part of the unit is exposed
intermittently along creek banks.
• Phosphatic nodules, siderite concretions filling
bioturbation structures, and thin sand beds are common
near the top of the unit.
• Sharks teeth and fossil shell molds are common
along with bone fragments and teeth of fish, reptiles,
and swimming dinosaurs near the top of the unit.
• Sedimentation patterns reflect storm-dominated
depositional patterns on a shallow shelf
environment.
• The thickness of the formation measures in the range of
70 to 100 feet.
Fossils of the Wenonah Formation
A - D. sharks teeth (an excellent guide to identifying sharks teeth is: Bretton W. Kent, (1994),
Fossil Sharks of the Chesapeake Bay Region. Columbia, MD: Egan Rees & Boyer, Inc., 146
p.); E. sawfish teeth; F. large fish scales; G. vertebrae, probably shark; H. molds of pelecypods
(Cardium wenonah) and gastropods (Lunatia halli; I. Coral. (An exceptional publication of fossil
descriptions with plates is: Horace G. Richards, etal., The Cretaceous Fossils of New Jersey,
Part 1 (1958) and Part 2 (1962); Trenton, NJ: Department of Conservation and Economic
Development.)
Late Cretaceous Units
• MT. LAUREL FORMATION - (latest Campanian,
Cretaceous) - The Mt. Laural is very similar in
appearance and composition to the underlying
Wenonah with the exception that it contains abundant
micaceous, glauconitic sand which is locally crossbedded.
• The unit contains an abundance of phosphatic peletal
material and bioturbation features; siderite concretions
commonly fill burrows.
• The unit is about 25 feet thick near Sandy Hook but
pinches out landward over a distance of several
miles beneath an unconformity beneath the overlying
Navesink Formation.
• The boundary between the underlying Wenonah is
undifferentiated in most areas east of the coastal area.
Common Mt. Laurel and Wenonah fossils include sharks
teeth and bone, shell molds, etc.
Late Cretaceous Units
• NAVESINK FORMATION - (early Maastrichtian,
Cretaceous) - The Navesink consists of peloidal
glauconitic marl and sand that is locally thick bedded
or crossbedded, and is locally clay-rich.
• Fossils are very abundant in some areas.
• Carbonaceous matter and phosphatic material, especially
at the base. Mollusk fossils are abundant in the lower
and middle portions of the unit.
• Common Navesink fossils include Belemnitella americana,
Expgyra costata, Expgyra cancellata, Pyncnodont sp.,
Ostrea falcata, Ostrea mesenterica, Choristothyris plicata,
and many others. (An small collection of Navesink
fossils is on diplay at the visitor's center at Poricy
Park, Monmouth County, NJ).
• The fossils occur in concentrated horizons within the unit.
The fauna suggest a marine shelf environment.
• It ranges in thickness between 65 to 45 feet throughout the
Atlantic Highlands region.
Fossils of the Navesink Formation
Mollusks: A-B:Exogyra cancellata, C: Pyncnodont mutabilis, D: Belemnitella
americana, E: Spondylus gregalis, F: Ostrea mesenterica, G: Ostrea falcata;
Braciopod: H. Choristothyris pilcata
Late Cretaceous Units
• REDBANK FORMATION - (Maastrichtian, Cretaceous) The Redbank Formation consists of gray to red sand
deposited in nearshore environments.
• Subaerial exposure at the end of "Redbank time"
resulted in the leaching of shell material and the
alteration of glauconite to limonite (hence the red
color).
• A lower brownish- black micaceous sand unit is called
the Sandy Hook Member and displays abundant
concretions in bioturbated horizons and has been
described as locally fossiliferous.
• The upper Shrewsbury Member is yellow to orange-gray
sand. The unit is a approximately 120 feet thick near
Sandy Hook along the valley of the Navesink and
Shrewsbury rivers, but grows progressively thinner until
it eventually pinches out landward.
Late Cretaceous Units
• TILTON FORMATION - (late Maastrichtian, Cretaceous)
- The Tilton is a massive "olive to evergreen" green
glauconitic quartz sand which is locally clay-rich and
silty.
• The unit displays an abundance of iron-staining and
locally bears limonite and hematite crusts and
concretions.
• Locally glauconite constitutes as much as 80% (or more)
of the sand, making portions of the formation an
economic greensand in the central Coastal Plain.
• Fossils, mostly poorly preserved molds and casts of
pelecypods, Camptonectes, are common, whereas a
richer marine fauna occurs further southward in central
New Jersey.
• The unit displays heavy bioturbation. The formation is in
the range of 20 to 25 feet thick.
The Cenozoic Era
• 65.5 million years ago to the present
• Name "Cenozoic" = "new life" or "recent
life"
Periods of the Cenozoic Era
• The Cenozoic Era consists of two periods
– Older Paleogene Period
– Younger Neogene Period
• The Paris Basin is the type area for most
of the epochs of the Cenozoic. There is a
major unconformity in the basin that was
chosen as the boundary between the
Paleogene and the Neogene.
Periods of the Cenozoic Era
• Until 2003, the two periods in the Cenozoic Era
were the Tertiary and Quaternary Periods. You
will see these terms on older maps and in older
publications.
• In 2003, the International Commission on
Stratigraphy revised the nomenclature, dropping
the terms Tertiary and Quaternary. The two
periods of the Cenozoic Era are officially
recognized as the Paleogene and the Neogene.
Cenozoic Time Chart
Paleogeography and Plate
Tectonics
• During the Cenozoic, the Atlantic and
Indian Oceans widened, and the
continents moved to their current
positions.
• Half of the present ocean crust has formed
at the mid-ocean ridges since the
beginning of the Cenozoic.
Tectonic and Paleographic Changes
and Their Effects on Climate
• The Panama land bridge blocked the westward
flow of the North Atlantic Current. The current
was deflected to the north (turning to the right,
as a result of the Coriolis Effect), and formed the
Gulf Stream.
• The Gulf Stream transported warm water
northward and resulted in bringing warmer
climates to northwestern Europe.
• Gulf Stream also supplied warm, moist air
toward the North Pole, which would ultimately
result in precipitation which helped build the
glacial ice sheets.
Important continental breakups:
1. North Atlantic rift separated Greenland from
Scandinavia
2. Australia separated from Antarctica.
Circumpolar currents isolated Antarctica from
warmer waters. Led to cooling of Antarctica.
3. Cold, dense ocean waters around Antarctica
drifted northward along ocean floor,
contributing to global cooling and the Ice Age.
4. Rifting occurred between Africa and Arabia,
forming the Red Sea and the Gulf of Aden.
North America During the
Paleogene
The Paleogene is dominated by:
– The deposition of marine sediments in
eastern and southeastern North America
Paleogene
Period
Eastern and Southeastern
North America
• Ridges and valleys of the Appalachian
Mountains were carved by erosion.
• As erosion proceeded, gentle isostatic
uplift occurred. This stimulated more
erosion, as streams cut downward.
Eastern and Southeastern
North America
Uplift in the eroding
Appalachians was
coupled with
downward tilting and
deposition of
sediments on the
Atlantic Coastal Plain
and continental shelf.
Sediments thicken
seaward forming a
clastic wedge.
Eastern and Southeastern
North America
• Eight marine transgressions and
regressions are recorded in Cenozoic
sediments on the Atlantic and Gulf Coastal
Plains.
• Carbonate sediments accumulated in
Florida where less terrigenous clastic
sediment was available.
Tertiary Units
• HORNERSTOWN FORMATION - (Danian, early
Paleocene) - A drastic change in fauna is
represent at the base of the Hornerstown in New
Jersey.
• This is a reflection of both a mass extinction
even as well as a hiatus in deposition.
• The formation is lithologically similar to the Tilton
consisting of a green glauconitic quartz sand.
• Cretaceous fossils have been noted reworked
upward into the basal units.
• Fossil in the Hornerstown include gastropods,
pelecypods, and other vertebrate bone material.
The unit displays heavy bioturbation.
Tertiary Units
• VINCETOWN FORMATION - (Paleocene to
Eocene) - The Vincetown consists of quartz
sand with phosphatic pellets and glauconite
ranging form nearly trace to nearly 100% in
some beds (glauconite being most abundant at
the base of the unit where it appears gradational
with the underlying Hornerstown).
• Near the shore fossils are absent, however, the
unit displays bioturbation structures.
• Elsewhere on the Coastal Plain it is extremely
fossiliferous containing abundant foraminifera,
bryozoa, and a prominent basal shell bed
containing Oleneothyris harlani, Gryphaea
dissimilaris, and bone fragments. Thickness is in
the range of 50 to 100 feet.
Tertiary Units
• MANASQUAN FORMATION - (Eocene) This unit is missing in the Atlantic
Highlands region, however, it crops out
along creek bottoms southward along the
Jersey Shore.
• It consists of a mixed shaley and sandy
marl with abundant apatite pellets and
siderite concretions, with fossils rare or
absent.
• Thickness (including Shark River) in the
range of 50 to 200 feet.
Tertiary Units
• SHARK RIVER FORMATION - (Eocene) - This
unit is also missing beneath the Cohansey Sand
in the Atlantic Highlands region, however, it
crops out along the creek banks of the Shark
River (as the name applies) and contains sharks
teeth.
• The unit consist of a sandy, carbonaceous
glauconitic marl and quartz sand.
• It lies conformably on the Manasquan below.
Some researchers do not differentiate Shark
River from the underlying Manasquan
Formation.
Tertiary Units
• KIRKWOOD FORMATION - (middle Miocene) - The
Kirkwood Formation is missing from the Atlantic
Highlands section beneath the Cohansey Sand.
• Further south the formation consists of a clayey to silty
mudrock, massive sand, and thin pebble lenses
deposited in a sublittoral to nearshore environments.
• The unit is equivalent to the Calvert, Choptank, and St.
Marys River formations in Maryland and Virginia.
• The sparse occurrence of Calvert cliffs fauna in beach
pebbles suggest that the Kirkwood-equivalent strata on
the continental shelf is fossiliferous. (This unit has been
suggested as time equivalent to the formation of the late
Tertiary Schooley Peneplane throughout the
mountainous Appalachian region.)
• The bottom of the Kirkwood sits unconformably in top of
older Tertiary units. The thickness is in the range of 100
to 300 feet in the Pine Barrens region.
Tertiary Units
• COHANSEY SAND - (late Miocene to early
Pliocene) - The formation consists of medium to
coarse-grained arkosic quartz sand (well
stratified and cross-bedded), with thin clay
lenses and quartz and quartzite pebble
conglomerate.
• The unit represents a range of sedimentary
environments ranging from fluvial to transitional
marine environments (swamps, deltas, lagoons,
beach sand, and shallow open marine shelf).
• Sediments at the base of the Cohansey appear
to fill broad fluvial channels carved downward
into the underlying formations (down to the Tilton
in the Atlantic Highlands region).
Tertiary Units
• COHANSEY SAND
• Many beds within the unit are heavily cemented
by iron; these ironstone sand and gravel
depositons form a resistant hilltop caprock in the
Highlands region.
• The Cohansey represents most of the surface
deposits throughout the New Jersey Coastal Plain
and is well exposed on hills and roadcut and sand
pits throughout the Pine Barrens region.
• All fossil material appears to be leached out of the
Cohansey (possibly by processes similar to the
acid waters and bog-iron formation currently
active in the Pine Barrens region.
• The unit ranges in thickness from a several
meters on hilltops to more than 150 feet on the
western side of the coastal plain.
Tertiary Units
• BEACON HILL FORMATION (Pliocene?) - An iron-stained sandy quartz
and quartzite-rich gravel deposit on top of
the highest hill in Monmouth County, NJ
(373 feet) probably represents a Pliocene
fluvial gravel equivalent to late deposition
the Cohansey Formation.
• The Beacon Hill caps Apple Pie Hill and
other small hills in the Pine Barrens
region.
Quaternary and Holocene
Deposits
• BRIDGETOWN FORMATION - (early
Pleistocene?) - The precise age of the
Bridgetown Formation is unclear, however, it
consists of a deeply weathered mix of silt, sand,
and gravel and represents fluvial environments.
• The Bridgetown probably represents
sedimentation during an earlier, preWisconsin interglacial stage. (Isphording &
Lodding, (1969) state that the Bridgetown and
Pensauken formations are virtually
indistinguishable along the coastal areas. Both
units lack fossils.)
Quaternary and Holocene Deposits
• PENSAUKEN FORMATION - (Late Pleistocene)
- Wisconsin till unconformably overlies this unit
that crops out along a trend from Staten Island
to Trenton, NJ and southward along the
Delaware River valley.
• The unit consist of mixed detritus (eroded from
older glacial material and exposed Coastal Plain
formations) that was deposited in fluvial flood
plain environments.
• The existence of the Pensauken formation
suggest that, for a time, the major drainage from
the pre-Wisconsin glaciers was southward from
the New York area toward Trenton into the
Delaware River drainage.
• Pedogenic weathering of the sediments suggest
that it was deposited during a warm interglacial
period.
Quaternary and Holocene
Deposits
• CAPE MAY FORMATION - (Late Pleistocene to
Holocene) - The Cape May formation consists of
surficial silts, sands and quartz-rich gravels
along the coastal region of New Jersey and
represents coastal beach and barrier sand
deposits and back bay estuarine deposits.
• The source of the sand is mostly from the
Delaware River drainage supplemented by shelf
sands and longshore drift sand from the MidAtlantic region.
• The progessive reworking of Cape May deposits
is the source of much sand on the New Jersey
coast.
Quaternary and Holocene
Deposits
• COLUMBIANA GROUP (early to late
Quaternary) consists of three named units - the
Pensauken, Bridgetown, and Cape May
formations (oldest to youngest, respectively) each represents different depositional
environments throughout the region.
• The Gardeners Clay is probably a marine
equivalent to the Pensauken Formation. Active
research in the region will no doubt refine the
correlation problems between Pleistocene and
Holocene sedimentary deposits as
investigations proceed on glacial deposits, and
lacustrine, swamp, terrestrial, fluvial, estuary,
nearshore and marine shelf deposits in the Bight
region.
Quaternary and Holocene
Deposits
• GARDENERS CLAY - This poorly consolidated
clay underlies Wisconsin Age glacial deposits
throughout southern Long Island and has been
interpreted as occurring beneath the modern
barrier spit of Sandy Hook.
• The Gardeners Clay contains a rich estuarine
fauna with abundant foraminifera. The unit
probably represents high-standing seas between
advances of the latest Pleistocene (Wisconsin)
glacier.
Quaternary and Holocene Deposits
• WISCONSIN GLACIAL TILL - Wisconsin glacial
deposits are apparent everywhere throughout Long
Island, across northern Staten Island and in northern
New Jersey.
• Glacial till consists of unstratified mix of clay, silt and
sand with a mix of rock material ranging from pebbles to
giant boulders (derived from all rock source areas
ranging from Manhattan to Central Quebec).
• The terminal moraine extends across central New Jersey
along a sinuous line from the vicinity of Perth Amboy to
around the Delaware Water Gap on the western side of
the state.
• Outwash sand and gravel deposits (altered by soilforming processes) cover much of southern Long Island,
southern Staten Island and areas south of the terminal
moraine in New Jersey.
• Varved lake clays and swamp peat cover areas flooded
by lakes.
Quaternary and Holocene
Deposits
• HOLOCENE DEPOSITS - The modern beach and barrier islands
around the New York Bight represent reworked sand material that
began accumulating during a slow-down in sea level rise that began
about 3-4,000 years ago.
• These modern coastal deposits overly older Holocene estuarine and
fluvial sediments deposited behind barriers that developed during a
period ranging from 12,000 to about 7,000 years ago. (These old
barrier deposits are partially eroded and/or buried by younger
sediments.
• These barriers existed anywhere from 2 to 20 kilometers
seaward of the current shoreline when sea level was
approximately 20 to 40 meters lower.
• On the continental shelf these ancient barriers are currently
supplying sediment to offshore sand ridges.
• Sand along the Hudson River and on Staten Island displays an
abundance of angular feldspar and lithic fragments indicative of
fluvial sedimentation in the harbor region when sea level was lower.
• Modern anthropogenic sediments and human activity has modified
nearly all coastal and nearshore marine sedimentary environments.
Cenozoic Paleoclimates
Global Surface Cooling
• There was a 10o C (18o F) temperature drop at
end of Cretaceous Period.
• Several warming trends occurred in the late
Paleocene and Eocene, as indicated by:
– Fossils of palm trees and crocodiles in
Minnesota, Germany, and near London.
– Fossils of trees from temperate zones in
Alaska, Norway and Greenland.
– Coral reefs in latitudes 10-20o closer to the
poles than at present.
Antarctica in the Paleogene
• The climate was semitropical and mild in
Antarctica during the Paleogene, as
indicated by fossil spores and pollen,
despite the fact that it sat on the South
Pole.
• Before Antarctica separated from
Australia, it was warmed by currents
moving southward from more equatorial
latitudes.
• Australia began to
separate from Antarctica
in the early Eocene,
about 55 m.y. ago.
• After separation,
circumpolar currents
developed around
Antarctica, cutting it off
from equatorial currents.
• This resulted in
temperature decrease
and glacial conditions
over Antarctica.
Global Surface Cooling
• Temperatures dropped by about 8-13o C
(roughly 22o F) near the Eocene-Oligocene
boundary, as indicated by isotope data from
brachiopods from New Zealand.
• Antarctic sea ice began to form by 38 m.y. ago.
• Greenhouse conditions were replaced by
icehouse conditions.
Worldwide cooling resulted in:
1. First Cenozoic widespread growth of glaciers in
Antarctica about 38-22 m.y. ago.
2. Global sea level dropped by about 50 m in the
Early Oligocene, as glaciers formed.
3. Cold, dense polar water flowed northward
across ocean bottom.
4. Upwelling of cold bottom waters affected world
climate.
5. Decrease in diversity and extinctions of many:
– marine molluscs
– planktonic and benthonic foraminifera
– ostracodes
6. Extinctions were earlier and more severe at
higher latitudes.
7. Reefs shifted toward the equator.
8. Calcarous biogenic deep sea sediments
(foraminiferal ooze) shifted toward the equator
and were replaced by siliceous biogenic
sediments (diatom and/or radiolarian ooze) at
higher latitudes.
9. Changes in pollen indicate long term cooling
and drying.
– Temperate and tropical forests shifted
toward the equator.
– Grasslands expanded.
– Rainforests became confined to tropical,
equatorial areas.
10. Glaciation occurred in other areas in Pliocene
(and younger) deposits - Sierra Nevada,
Iceland, South America, and Russia.
Antarctic Bottom Waters
• The cold waters around Antarctica were dense,
and sank to the ocean floor around Antarctica.
(Cold water is denser than warmer water.)
• Cold, dense ocean-floor waters moved
downward and outward, away from Antarctica.
• The northward movement of cold dense waters
contributed to cool conditions during the late
Eocene and early Oligocene, and ultimately led
to the Pleistocene Ice Age.
The Pleistocene
• The Pleistocene began 1.8 m.y. ago.
• The most extensive glaciations began about
1 m.y. ago.
• The end of the Pleistocene is when the ice
sheets melted to approximately their current
extent.
• The Pleistocene-Holocene boundary is placed
between about 12,000 and 11,000 years ago, at
the midpoint of the warming of the oceans.
• This coincides with a rise in sea level.
The Pleistocene Ice Age
• The Pleistocene is significant as the time in
which humans evolved.
• More than 40 million km3 of snow and ice
covered about 1/3 of Earth's land area.
• Continental glaciers covered much of North
America and Europe.
• Alpine glaciers covered parts of the Cordilleran
Mountain range in western North America, the
Alps, and other mountain ranges of Europe.
Pleistocene continental glaciers in the Northern Hemisphere
As a result of the Ice Age:
1. Climatic zones in the Northern Hemisphere
were shifted southward.
2. Arctic conditions prevailed across Europe and
the U.S.
3. Sea level dropped as much as 75 m (225 ft)
and the shoreline shifted seaward, exposing
the continental shelves as dry land.
4. Streams cut deep canyons into the continental
shelves and on land.
5. Land bridges existed and led to migrations of
mammals, including humans
– Across the Bering Sea between Siberia and
Alaska
– Between Australia and Indonesia
– British Isles were attached to Europe
6. The land was sculpted by glaciers in Europe
and North America.
7. U-shaped valleys formed in mountainous
areas
8. Rainfall increased at lower latitudes.
9. Large lakes formed in the Basin and Range
Province.
– Lake Bonneville in Utah covered more than
50,000 km2 and was about 1000 ft deep in
places.
– The Great Salt Lake is a small remnant of
Pleistocene Lake Bonneville.
– The Bonneville salt flats were formed as the
lake evaporated.
10. Winds coming off glaciers blew sediment
southward forming löess deposits (Missouri
River area, central Europe, northern China)
11. Parts of northern and eastern Africa that are
currently arid had abundant water and were
fertile and populated by nomadic tribes.
12. Nomadic tribes hunted along the edges of the
continental glaciers. Wild game was abundant,
furs provided warm clothing, and there were
less problems with spoiled meat in the cold
temperatures.
13. Formation of the Great Lakes (depressions
scoured by glaciers and flanked by moraines)
14. Formation of Cape Cod, MA - a moraine
15. Formation of Long Island, NY - a terminal
moraine
16. Formation of Niagara Falls
17. Formation of large ice-dammed lakes,
including Lake Missoula which drained
catastrophically, forming the channeled
scablands
18. Formation of hummocky topography and
Pleistocene sand dunes
19. Weight of the ice
depressed the
continental crust
to as much as
200-300 m
downward.
20. Uplift (isostatic
rebound) after
ice melted.
Coastal features
are now elevated
high above sea
level.
Map illustrating post-glacial uplift
in North America.
Names of the
"traditional"
glacial and
interglacial
stages in North
America