Florida’s Geology The physical materials of Florida Week of January 12, 2015
Transcript
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The physical materials of Florida Week of January 12, 2015
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Geology = Geo-, Latin for earth. = Why study it for Florida
Ecology?
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Geologic Time Florida Broke to the surface as land 35 to 25
million years ago (mya) The bedrock of Florida accumulated for
millions of years
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Building a Foundation Pangea = a supercontinent (~550mya) and
the separation of the continents through continental drift.
Floridas limestone bedrock was attached to Africa, in a rift, then
pulled apart with the North American continent.
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Evidence for Pangea Same rocks and sediments and fossil
deposits containing same species discovered on separate
continents--- separated by Atlantic Ocean Continents appear to fit
together like puzzle pieces
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How did Pangea break apart? Theory of Continental Drift, 1950s
and 60s. Earth crust made up of many plates The boundaries where
ocean plates meet are mid-ocean ridges. New sea floor created here.
Other plate boundaries responsible for volcanoes, earthquakes,
mountain building
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Evidence for Continental Drift Young sea floor (at a ridge) had
little time to accumulate sediments Rocks are older and sediment is
thicker as you move away from the ridge The rocks of the sea floor
show the earths magnetism at the time of their cooling = magnetic
anomalies.
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Florida as Africa Floridas limestone bedrock was attached to
Africa, in a rift, then pulled apart with the North American
continent. Florida's Movement
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Major Eras in the Natural History of Earth 1) Paleozoic:
550-250 mya Early Animal Life in the Oceans Fishes Diversify Ferns
and Early plants begin to colonize land 2) Meozoic: (250 to 65 mya)
Reptiles Diversify, Age of Dinosaurs Gymnosperm Plants = most
softwoods with seeds in cones diversify 3) Cenozoic :(65 mya to
Present) Mammals diversify Flowering plants =Angiosperms, Harwoods
Diversify Florida Emerges as a LANDMASS
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Cenozoic Era: 65 mya to Present Tertiary Period Paleocene 65-53
mya Eocene53-34 mya Oligocene34-23 mya (Florida Emerges at end
here) Miocene23-5 mya Pliocene5-2 mya Quarternary Period
Pleistocene Epoch 2mya to 10,000 years ago Holocene (Recent)10,000
years ago to present
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Florida as a Landmass Earlier shorelines determined by looking
at fossils in marine deposits Florida has changed size in the past
35 million years High sea level/Interglacial warmer climate =
island chains Low sea level/Ice ages = twice the present landmass
Panhandle emerged ~25 mya Last time peninsula underwater 23
mya
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Florida Platform - limestone dominated flat topped structure 3
components of Platform 1) Basement rock-Paleozoic & some
Mesozoic 2) Carbonate rock- Mesozoic & Cenozoic era 3)
Siliciclastic sediments (mostly quartz sand)- Cenozoic era 1) and
partially 2) when still part of Gondwana (Africa)
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Paleocene and Miocene 65-34 mya
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Many fossils from this time period are found: Sea grass fossils
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Oligocene 34-23 mya Late Oligocene 25-23 mya FL many islands
before complete emergence Late Oligocene: Sea level fell ~ 300 ft.
Florida Emerges ~ 24 mya. Gulf Trough a narrow inlet or estuary,
but filling in Fossils from this time period:
Oligocene 34-23 mya Read and record about Oligocene
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Miocene 23-5 mya Gulf Trough filled in Parts of FL repeatedly
submerged and exposed Freshwater communities emerging Diverse
Animals:
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Miocene 23-5 mya Read and record about Miocene
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Pliocene 5-2mya Inter-glacial Period, Warm Climate High Sea
Level North American continent is dry FL has enough water resources
to support Mammal Diversity on semi-arid savannahs and subtropical
forests
Megalonyx jeffersoni Giant ground sloths 8-10 feet, up to 800
lbs Vegetarian, Foraged on trees.
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Mammuthus- Wooly Mammoth Mammut- American Mastodon
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Pleistocene 2mya to 10,000 ybp Many of these same animals went
extinct in the late Pleistocene. Another ice age occurred, Colder
climate Low sea level A landbridge between N and S. America forms
allowing for long isolated species to travel North and South. The
Great American Biotic Interchange
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The Great American Biotic Interchange During Late
Pliocene/Early Pleistocene From South America From North America
Opossum Armadillo Flying Squirrel Vampire Bats Lots of Frogs
Hummingbirds Raccoon Llama Coral Snakes Many Pit Vipers Jaguar
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Formation of the Gulf Stream Remember: Ice Age, Low Sea Level,
Central America Appearing. Blocked Pacific from the Atlantic
Diverted Ocean Currents Gulf Stream created! Altered Climate Warm
air and water moving to poles, cooled to make precipitation,
creating much more snow and ice. Ice caps grew and repeated Ice
Ages.
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Coral Reef Formation around Florida Gulf Stream also took away
nutrients from the warm waters, making ideal conditions for coral
reefs to become established. Evolution of Staghorn and Elkhorn
Coral Species
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Pleistocene continues The Bering land bridge was also exposed
during these global ice ages, allowing Asian species to migrate to
North America. Long-horned Bison
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Holocene Period ~20,000 years ago to Present Periods of warming
and cooling continue on a smaller scale Humans arrive to N. America
via Bering Land Bridge Most mammal megafauna extinct, due to:
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Southeastern U.S Coastal Plain Florida a part of this region.
Area of sediments that spreads from the southern Appalachian Mtns.
Piedmont to the coasts Piedmont = a rocky skirt that surrounds
mountains
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Florida: 3 layers of sediments Sediments = loose materials
deposited on the land or at the bottoms of water bodies 1)
Fragments of rocks from land 2) Materials formed beneath the sea 3)
Organic matter
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Floridas Bedrock Bottom layer: Marine sediments Build-up of
ancient marine sediments Originate from salts, dead organisms with
shells that settle out of ocean waters Floridas major ones:
Limestone & Dolomite Calcium carbonate and Magnesium
carbonates
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Middle Layer: Clastic Sediments Loose Clastic sediments
Fragments of rock Mostly Quartz (Silicon Dioxide SiO 2 ) and
Feldspar (Aluminum Silicates AlSi # O # ) From erosion of
Appalachian Mtns. In form of clay, silt, sand, gravel
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Top layer: Soil= particulate material lying a lop land, which
is capable of supporting plant life. Mixture of Marine and Clastic
Sediments with Organic Materials Vary in Size of sediments Vary in
pH from Acidic to Alkaline Vary in ability to retain water Xeric
Mesic Hydric 300 types of soils in Florida contribute to the
diversity of our ecosystems.
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Soil Types Xeric Dry Soils Rain water drains rapidly Contains
ample oxygen to meet plants needs Mesic Moist soils that do not
become waterlogged Drain well and hold oxygen Hydric Wet soils, may
becomes waterlogged Low oxygen concentrations