Download Geologic Origin of of Lakes Part 2 - Aquatic Ecology

Kettle Lakes on Pitted Outwash Plain
Fjord Lake – glacial rock-basin lakes
• A limnologically important
feature of many marine &
estuarine fjords is the
presence of a partial dam
of rock or moraine near
the mouth, which
prevents full circulation
w/ the ocean.
• Saltstraumen, Norway
Thaw (Cryogenic) Lakes – perennially frozen
ground=permafrost
Continental
Glaciation:
Finger Lakes
Modified by glaciers. The present lakes
were preglacial stream
valleys or earlier lakes
.
Lakes of Tectonic Origin
• Old, deep lakes & many of the World’s largest
lakes
• Many formed during or before Pliocene era (110 million yrs. Ago)
• New Disaster: Reserviours, Lakes in danger
after quake China
Graben Lake: Tahoe
grabens=single or multiple faults
Rift Graben Lake: Baikal
More Rift Lakes
Volcanic Lakes: Crater Lake
Crater Lake, Oregon (10km across,
600m deep)
Lakes w/ Other Origins
Extraterrestrial Forces:
Astroblemes
Manicougan
Chubb Lake - formed when meteors hit the Earth and formed large
depressions which filled with water
Sinkhole Lake
Sinkhole Lake Formation
• Dissolution of soluble rock by dilute acids in water
percolating through it.
• Results in small caves that are usually small and steepsided.
• Limestone
Oxbow Lake
http://www.school-portal.co.uk/GroupDownloadFile.asp?file=21606
• Loop of a
meandering
river is cut off
by silt
deposition.
Oxbow cutoff to form separate lake
Biological
Formations
-Animals
Beaver Dam
Lakes
-Reservoirs
Anthropogenic Lakes
• Based on the reading in Ch.11, how do you
think Lake Manahawkin was created?
Dam Disasters
• Raw Video: Heavy Rains Cause Iowa Dam
Break
• Raw Video: House Crashes Into Bridge
Origins of Wetlands
• Similar to lakes (glaciation, tectonic effects,
volcanism), except wetlands are shallow.
• <1m of water.
• Some marshes swamps and bogs formed from filled
in lakes.
• Riparian vegetation becomes established when river
becomes stable and forms a delta.
• How can climate affect these areas?
Origins of Estuaries
• Geologic events that turn rivers into lakes will
create estuaries near the ocean.
• Most originate from glacial melt & some from
tectonic processes.
• Can also be produced from large tidal delta
regions by sedimentation where large rivers
meet the sea.
Coastal Plain Estuaries
• Coastal plain estuaries
formed during the end of
the last ice age. At this
time, sea level rose
because of melting ice and
warming ocean
waters. The rising water
flooded coastal river
valleys, forming
estuaries. The Cape Fear
River estuary is a coastal
plain estuary.
Chesapeake Bay
Barnegat Bay
Bar-Built Estuaries
• Bar-built estuaries are
found where sand bars
form on a coastline. The
water behind the sand
bars are partly cut off
from the sea. The
Albemarle-Pamlico Sound
behind the Outer Banks is
a bar-built estuary.
San Francisco Bay, California - A
tectonic estuary
Photo courtesy of the U.S. Geological Survey
Glacier Fjord
• Fjords are deeply cut
valleys that are
formed by the
movement of
glaciers. When
glaciers moved north
at the end of the last
ice age, the sea filled
in the valleys and
formed estuaries.
•
Photo courtesy of the National Aeronautics and
Space Administration (NASA)
Mississippi River – Estuaries produced
from deltas