The physical materials of Florida
Week of January 12, 2015
Geology =
Geo- , Latin for earth.
=
Why study it for Florida Ecology?
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
Building a Foundation
 Pangea = a
supercontinent
(~550mya) and the
separation of the
continents through
continental drift.
 Florida’s limestone
bedrock was attached to
Africa, in a rift, then
pulled apart with the
North American
continent.
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”
How did Pangea break apart?
 Theory of Continental Drift, 1950’s and 60’s.
 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
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 earth’s
magnetism at the time of
their cooling = magnetic
anomalies.
Florida as Africa
 Florida’s limestone bedrock was attached to Africa, in
a rift, then pulled apart with the North American
continent.
 Florida's Movement
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
Cenozoic Era: 65 mya to Present
 Tertiary Period
 Paleocene
65-53 mya
 Eocene
53-34 mya
 Oligocene
34-23 mya (Florida Emerges at end here)
 Miocene
23-5 mya
 Pliocene
5-2 mya
 Quarternary Period
 Pleistocene Epoch
2mya to 10,000 years ago
 Holocene (Recent)
10,000 years ago to present
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
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)
Paleocene and Miocene
65-34 mya
Paleocene and Miocene
65-34 mya
 Many fossils from this
time period are found:
 Sea grass fossils
-
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
 Insects, bats, birds, tortoise
 Land Mammals
 (Beaver, deer, rodent, rabbit, anteater, goat, horse, pig) like
creatures
 Opposum
 Saber-toothed cats
Oligocene 34-23 mya
Read and record about Oligocene
Miocene 23-5 mya
 Gulf Trough filled in
 Parts of FL repeatedly submerged and exposed
 Freshwater communities emerging
 Diverse Animals:
Miocene 23-5 mya
Read and record about Miocene
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
Pliocene Megafauna
 Horse
 Camelid
 Glyptodont
 Sloth
 Mammoth
 Mastodon
 Giraffoid
 Rhinoceroid
 Long nosed Peccaries
Megalonyx jeffersoni
 Giant ground sloths
 8-10 feet, up to 800 lbs
 Vegetarian, Foraged on
trees.
Mammuthus- Wooly
Mammoth
Mammut- American
Mastodon
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
The Great American Biotic Interchange
…During Late Pliocene/Early Pleistocene…
From South America
From North America
 Opossum
 Raccoon
 Armadillo
 Llama
 Flying Squirrel
 Coral Snakes
 Vampire Bats
 Many Pit Vipers
 Lots of Frogs
 Jaguar
 Hummingbirds
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.
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
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
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:
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
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
Florida’s Bedrock
Bottom layer: Marine sediments
 Build-up of ancient
marine sediments
 Originate from salts,
dead organisms with
shells that settle out of
ocean waters
 Florida’s major ones:
 Limestone & Dolomite
 Calcium carbonate and
Magnesium carbonates
Middle Layer: Clastic Sediments
 Loose Clastic sediments
 Fragments of rock
 Mostly Quartz (Silicon
Dioxide SiO2) and
Feldspar (Aluminum
Silicates AlSi#O#)
 From erosion of
Appalachian Mtns.
 In form of clay, silt,
sand, gravel
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
300 types of soils in Florida
contribute to the diversity of
our ecosystems.
 Mesic
 Hydric
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