Transcript powerpoint presentation

Improving Ocean Literacy
By Teaching the
Geology of Lake Huron
David P. Lusch, Ph.D., GISP
Dept. of Geography
Michigan State University
NSTA Northern/Midwestern Area Conference, Detroit, MI
October , 2007
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Ocean Literacy Concept Map, Grades 3 – 5
Subset that are covered using
Geology of Lake Huron
2. The ocean and life in the ocean shape the features
of the earth
2.1 Some landforms we see today were once
underwater
2.2 Movement of water erodes and deposits materials
(sediments)
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Ocean Literacy Concept Map, Grades 3 – 5
2.1 Some landforms we see today were once
underwater
2.1.1 Forces underneath landmasses and the sea floor
(tectonics) can change the shape of the earth’s
surface
2.1.2 Changes in sea level shape the earth’s surface
2.1.2.1 During ice ages, sea level falls; during periods of
warm climates, sea level rises
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Ocean Literacy Concept Map Grades, 3 – 5
2.1 Some landforms we see today were once
underwater
2.1.3 Some rocks found on land were formed in the
ocean
2.1.3.1 Sedimentary rocks form when ocean sediments are
compressed
2.1.3.2 Organisms embedded in sedimentary rocks become
fossils
2.1.3.2.1 Marine fossils can be found in various types of
sedimentary rocks, especially shale and
limestone
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Ocean Literacy Concept Map Grades, 3 – 5
2.2 Movement of water erodes and deposits
materials (sediments)
2.2.1 Rivers carry sediments downstream to the oceans
(clastic sediments)
2.2.2 The facies concept explains lateral variations in
the lithologic characteristics of sediments of the
same geological age
2.2.2.1 Wave energy in the shore zone keeps the finer
clastic sediments in suspension
2.2.2.2 Fine clastic sediments settle out in the off-shore
clastic zone
2.2.2.3 Carbonate-rich sediments are deposited in the
deeper off-shore, non-clastic zone
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Canadian
Shield
Michigan
Sedimentary
Basin
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Michigan Sedimentary Basin
 Michigan Basin was inundated numerous times
by oceans, which eventually filled it with
sedimentary deposits
 Four general sedimentary rock types fill the
Michigan Basin:
 Sandstones
 Carbonates (limestone and dolostone)
 Shales
 Evaporites (halite and gypsum)
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Michigan Sedimentary Basin
 Younger rocks (542 – 145 million years old)
 All sedimentary (mostly marine deposits)
 Sandstone
 Shale
 Carbonates (Limestone and Dolostone)
 Variably resistant to erosion
 Sandstone and carbonates resist physical erosion
 Shale is soft, thinly bedded and easily eroded
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Cambrian 500 Ma
N
X
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What a difference 20 million years makes!
N
N
Mississippian
345 Ma
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Mississippian
325 Ma
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Facies Concept
 Lateral variations in the lithologic characteristics
of a volume of sediments of the same geologic
age
Wave energy
keeps fine clastic
sediments in suspension
Near-shore
zone
Becomes
sandstone
No wave energy fine clastic
sediments settle out
Off-shore
clastic zone
Becomes
shale
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No wave energy no clastics
non-clastic sediments
settle out
Off-shore
non-clastic zone
Becomes
limestone/
dolostone
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Differential erosion
 Sedimentary rock types are of unequal
resistance to physical erosion:
 Sandstones and Carbonates are stronger and tend
to support highlands
 Shales are weaker and tend to underlie lowlands
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Michigan Sedimentary Basin
 Structural basin – like nested bowls
 Oldest rocks at the bottom, youngest at the top
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Niagaran Escarpment
 Major resistant-rock (dolomite) landform in the
Michigan Structural Basin
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Niagaran Escarpment
Bruce Peninsula, Ontario
Scarp
slope
N
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Bedrock of the Lake Huron Basin
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Bathymetry of the Lake Huron Basin
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Bathymetry of the
Lake Huron Basin
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 Origin of the Great Lakes
 Distal causes
 For Lake Superior - plate tectonics and rifting
 For the lower Great Lakes - development of the Michigan
sedimentary basin
 Proximal causes
 Glacial sculpting of bedrock, mediated by differences
in resistance to erosion
 Isostatic uplift of the region shifting the watershed
outlet
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 Beginning about 15,500 C14 years ago, the
melting Ice Sheet began uncovering Lower
Michigan.
 A series of proglacial lakes formed at the margin
of the retreating Ice Sheet wherever the land
sloped towards the ice
front.
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Glacial Lake Elkton
12,400 C14 yrs ago
Glacial
Lake
Elkton
(Lundy)
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 Lake levels in the Great Lakes Basin
progressively fell as new outlets were
uncovered and down-cut.
 Eventually, the water levels in the Huron Basin
reached their lowest elevation when
drainage shifted to the final outlet at North
Bay, Ontario, which flowed eastward along
the Ottawa River Valley.
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ISOSTATIC REBOUND
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 Isostatic rebound evidence
Algonquin 11,000 C14 yrs
184.4 m
51.8 m rise in 6500 yrs.
Algonquin wave cliffs
Nipissing 4500 C14 yrs
184.4 m
Nipissing wave cliff
Nipissing wave cliff
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The End
http://www.rsgis.msu.edu/
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