Historic Florida…..In the Beginning - Part I

Although the written record of Florida doesn’t begin until the writings of Ponce de Leon’s explorations of 1513, human evidence has been traced to the first Native Americans 12,000 to 14,000 years ago. However, to take a step even farther back, scientists believe they can trace the history of the state to millenia before humans walked it’s shores.  It’s always best to start at the beginning, so to truly understand the history of Florida, we must venture back to the very origins of the earth.

The earth and the rest of the solar system are thought to have originated about 4.5 billion years ago from a cloud or clouds of dust. This dust was debris remaining from a huge cosmic explosion called the big bang, which astrophysicists estimate occurred about 15 billion years ago. The dust particles collided with each other, merging into larger particles. These larger particles collided in turn, joining into pebble-sized rocks that collided to form larger rocks, and so on. The process continued, eventually building up the earth and other planets.

So much heat was produced as the early earth formed that the planet was probably molten. This allowed materials to settlewithin the planet according to their density. Density is the weight, or more correctly, the mass, of a given volume of a substance. Obviously, a pound of styrofoam weighs more than an ounce of lead, but most people think of lead as "heavier" than styrofoam. This is because lead weighs more than styrofoam if equal volumes of the two are compared. In other words, lead is denser than styrofoam. The density of a substance is calculated by dividing its mass by its volume. If two substances are mixed, the denser material will tend to sink and the less dense will float. During the time that the young earth was molten, the densest material tended to flow toward the center of the planet, while lighter materials floated toward the surface. The light surface material cooled to make a thin crust. Eventually, the atmosphere and oceans began to form. If the earth had settled into orbit only slightly closer to the sun, the planet would have been so hot that all the water would have evaporated into the atmosphere. With an orbit only slightly farther from the sun, all the water would be perpetually frozen. Fortunately for us, our planet orbits the sun in a narrow zone in which liquid water can exist. Without liquid water, there would be no life on earth.

The earth is composed of three main layers: the iron-rich core, the semiplastic mantle and the thin outer crust. The crust is the most familiar layer of earth. Compared to the deeper layers it is extremely thin, like a rigid skin floating on top of the mantle. The composition and characteristics of the crust differs greatly between the oceans and the continents

Since all life came from the sea, we will start there, beginning when the Earth including what is now Florida, formed about  4.5 billion years ago. The ocean is not just there to cover land. The sea floor is geologically distinct from the continents. It is locked in a perpetual cycle of birth and destruction that shapes the ocean and controls much of the geology and geological history of the continents. Geological processes that occur beneath the waters of the sea affect not only marine life, but dry land as well. The processes that mold ocean basins occur slowly, over tens and hundreds of millions of years. On this timescale, where a human lifetime is but the blink of an eye, solid rocks flow like liquid, entire continents move across the face of the earth and mountains grow from flat plains. To understand the sea floor, we must learn to adopt the unfamiliar point of view of geological time. Geology is very important to marine biology. Habitats, or the places where organisms live, are directly shaped by geological processes. The form of coastlines; the depth of the water; whether the bottom is muddy, sandy, or rocky; and many other features of a marine habitat are determined by this geology. The presence of large amounts of liquid water makes our planet unique. Most other planets have very little water, and on those that do, the water exists only as perpetually frozen ice or as vapor in the atmosphere. The earth, on the other hand, is very much a water planet. The ocean covers most of the globe and plays a crucial role in regulating our climate and atmosphere, and as a direct result, our history. Without water, life itself would be impossible.

Although the Theory of Plate Tectonics only came about in the 1960s, the process has ben going on for billions of years. Plate Tectonics is what explains seafloor spreading and continental drift.  Tectonic plates are solid bodies of rock floating on top of the asthenosphere, the upper mantle of the earth, an area that is partially molten. The plates themselves are what make up the lithosphere, which is the Earth's crust and the solid portion of the upper mantle. The lithosphere is cooler, heavier, and more rigid than the asthenosphere and is made up of seven large plates including: the African Plate, the Antarctic Plate, the Indo-Australian Plate, the Eurasian Plate, the North American Plate, the South American Plate, and the Pacific Plate.

Continental crust and oceanic crust behave differently due to their varying composition, so scientists named two types of lithosphere: the continental lithosphere and the oceanic lithosphere. Oceanic lithospheres are denser than continental lithospheres due to the high  silicate mineral content in the ocean.

Plates move in four different ways: convergent, divergent, collisional, and transform boundaries. As these moving plates meet along their boundaries, earthquakes are caused and volcanoes, mountains, and oceanic trenches are formed. Convergent boundaries occur where two plates slide towards each other and form a subduction zone, where plates slide underneath each other or on a collisional boundary where plates simply collide and compress. When a dense oceanic plate collides with a less-dense continental plate, the oceanic plate is usually pushed underneath, forming a subduction zone where the ocean floor looks like an oceanic trench on the ocean side and a mountain on the continental side. A subduction zone is found on the western coast of South America where the oceanic Nazca Plate is in the process of subduction beneath the continental South American Plate. The continental spine of South America is dense with volcanoes. These volcanoes are formed by the transfer and friction heating of organic material from the bottom, a process that releases many dissolved gases that can erupt to the surface.

Another example is the  Cascade mountain range in North America, which extends north from California's Sierra Nevada range. Volcanoes such as these are known for long periods of quiet and episodic eruptions starting with the expulsion of explosive gas containing fine particles of glassy volcanic ash and spongy cinders. A rebuilding of the pressure with hot magma follows this phase. The Pacific Ocean is completely surrounded by volcanoes; hence, it is called The Pacific Ring of Fire. Crumpling of both plates or compression of one plate occurs when two continental plates collide and one overrides the other. For example, the Himalayas were formed when an Indian subcontinental plate was thrust under part of the Eurasian plate. In Japan, it is common to see two oceanic plates converging to form an island arc as one plate is subducted under the other plate.

Divergent boundaries occur where two plates slide apart. The space created here is filled up with crust newly brought up from molten magma below. The  East African Great Rift Valley is an example of a rift formed by a divergent boundary. Divergent boundaries most likely form at hotspots where convective cells bring large quantities of molten material from the asthenosphere up and there is enough kinetic energy to break through the lithosphere. The Mid-Atlantic Ridge is thought to have come from a hotspot that widens a few centimeters every century. Hotspots may be a future source of energy as they are thought to be an abundant source of hydrogen. Countries like Iceland are actively researching  geothermal energy as a source for the world's first hydrogen economy.

Tectonic plates are able to move because they float on the relatively fluid asthenosphere. The source of energy for the movement of tectonic plates is thought to be the loss or dissipation of heat from the mantle of the Earth. Dissipation of heat from the mantle is converted into two forces, the force of friction and the force of gravity.

The transmission of convection currents in the mantle through the asthenosphere is driven by the force of friction occurring between the asthenosphere and the lithosphere known as mantle drag. Trench suction occurs when local convention currents pull plates at subduction zones and ocean trenches downward with the force of friction.

Gravity is another force in the movement of tectonic plates. There are several different types of plate motion caused by gravity including ridge-push plate motion and slab-pull plate motion. With ridge-push plate motion plates at oceanic ridges are higher in elevation and are prone to sliding down due to the force of gravity. The name is actually not representative of what is actually happening, since there is no pushing going on but rather the sliding down of plates. The underlying cause of motion is upwelling from the convection occurring in the mantle, and this is what triggers the sliding of plates. Slab-pull plate motion is the other gravitational force and is the result of cold, dense plates sinking into the mantle at places where there is a trench.

Over long periods of time, approximately every 500 million years, supercontinents form and break up. For example, the supercontinent known as  Rodinia formed approximately a billion years ago and was the starting material for all the current Earth's continents. About 750 million years ago, this supercontinent broke up into eight different continents which then formed two supercontinents called  Laurasia (North America, Europe and Siberia/Asia) and  Gondwana (China, India, Africa, South America, and Antarctica) about 350 million years ago which then reassembled about 275 million years ago to form what is known as the supercontinent Pangaea. Tectonic forces then began breaking Pangaea apart which continues today. The Earth is not the only planet where plate tectonics can occur. It is thought from observations made in 1999 of the magnetic fields of Mars by the Global Surveyor spacecraft that plate tectonics may have once been at work on Mars.

It is these plates that form the continental shelf. The continental shelf is the extended perimeter of each continent and it’s associated coastal plain. It was part of the continent during the glacial periods, but is undersea during interglacial periods such as the current epoch by relatively shallow seas, known as shelf seas, and gulfs.

The continental margin, between the continental shelf and the abyssal plain, comprises a steep continental slope followed by the flatter continental rise. Sediment from the continent above cascades down the slope and accumulates as a pile of sediment at the base of the slope, called the continental rise. Extending as far as 500 km from the slope, it consists of thick sediments deposited by turbidity currents from the shelf and slope. The continental rise's gradient is intermediate between the slope and the shelf.

Our ocean covers 72% of the earth's surface and is not distributed equally with respect to the Equator. About two-thirds of the earth's land area is found in the Northern Hemisphere, which is only 61% ocean. About 80% of the Southern Hemisphere is ocean.

The ocean is traditionally classified into four large basins. The Pacific is the deepest and largest, almost as large as all the others combined. The Atlantic "Ocean" is a little larger than the Indian "Ocean", but the two are similar in average depth. The Arctic is the smallest and shallowest. Connected or marginal to the main ocean basins are various shallow seas, such as the Mediterranean Sea, the Gulf of Mexico and the South China Sea.

Though we usually treat the oceans as four separate entities, they are actually interconnected. This can be seen most easily by looking at a map of the world as seen from the South Pole. From this view it is clear that the Pacific, the Atlantic and Indian oceans are large branches of one vast ocean system. The connections among the major basins allow seawater, materials, and some organisms to move from one "ocean" to another. Because the "oceans" are actually one great interconnected system, oceanographers often speak of a single world ocean. They also refer to the continuous body of water that surrounds Antarctic as the Southern Ocean.

.The geological distinction between ocean and continents is caused by the physical and chemical differences in the rocks themselves, rather than whether or not the rocks happen to be covered with water. The part of earth covered with water, the ocean, is covered because of the nature of the underlying rock.

Oceanic crustal rocks, which make up the sea floor, consists of minerals collectively called basalt that have a dark color. Most continental rocks are of general type called granite, which has a different mineral composition than basalt and is generally lighter in color. Ocean crust is denser than continental crust, though both are less dense than the underlying mantle. The continents can be thought of as thick blocks of crust "floating" on the mantle, much as icebergs float on water. Oceanic crust floats on the mantle too, but because it is denser it doesn't float as high as continental crust. This is why the continents lie high and dry above sea level and oceanic crust lies below sea level and is covered by water. Oceanic crust and continental crust also differ in geological age. The oldest oceanic rocks are less 200 million years old, quite young by geological standards. Continental rocks, on the other hand, can be very old, as old as 3.8 billion years.

In the years after World War II, sonar allowed the first detailed surveys of large areas of the sea floor. These surveys resulted in the discovery of the mid-oceanic ridge system, a 40,000 mile continuous chain of volcanic submarine mountains and valleys that encircle the globe like the seams of a baseball. The mid-oceanic ridge system is the largest geological feature on the planet. At regular intervals the mid-ocean ridge is displaced to one side or the other by cracks in the earth's crust known as transform faults. Occasionally the submarine mountains of the ridge rise so high that they break the surface to form islands, such as Iceland and the Azores.

The portion of the mid-ocean ridge in the Atlantic, known as the Mid-Atlantic Ridge, runs right down the center of the Atlantic Ocean, closely following the curves of the opposing coastlines. The ridge forms an inverted Y in the Indian Ocean and runs up the eastern side of the Pacific. The main section of ridge in the eastern Pacific is called the East Pacific Rise. Surveys also revealed the existence of the system of deep depressions in the sea floor called trenches. When the mid-ocean ridge system and trenches were discovered, geologists wanted to know how they were formed and began intensively studying them. They found that there's a great deal of geological activity around these features. Earthquakes are clustered at the ridges, for example, and volcanos are especially common near trenches. The characteristics of sea floor rocks are also related to the mid-oceanic ridges. Beginning in 1968, a deep-sea drilling ship, the Glomar Challenger, obtained samples of the actual sea floor rock. It was found that the farther rocks are from the ridge crest the older they are. One of the most important findings came from the studying the magnetism of rocks on the sea floor. Bands of rock alternating between normal and reversed magnetism parallel the ridge.

It was the discovery of the magnetic anomalies on the sea floor, together with other evidence, that finally led to the understanding of plate tectonics. The plates are about 100 km thick. As new lithosphere is created, old lithosphere is destroyed somewhere else, otherwise, the earth would have to constantly expand to make room for the new lithosphere. The old lithosphere is destroyed at the trenches. Additionally, as subduction occurs causing underwater earthquakes ans volcanoes, the volcanoes may rise from the sea floor to create chains of volcanic islands.

We now realize that the earth's surface has undergone dramatic alterations. The continents have been carried long distances by the moving sea floor, and the ocean basins have changed in size and shape. In fact, new oceans have been born. Knowledge of the process of plate tectonics has allowed scientists to reconstruct much of the history of these changes. Scientists have discovered, for example, that the continents were once united in a single supercontinent called  Pangaea which began to break up about 180 million years ago. The continents have since moved to their present position.

The chemical characteristics of seawater are due both to the nature of pure water and to the materials dissolved in it. The solids dissolved in seawater come from two main sources. Some are produced by the chemical weathering of rocks on land and are carried to sea by rivers. Other materials come from the earth's interior. Most of these are released into the ocean at hydrothermal vents. Some are released into the atmosphere from volcanoes and enter the ocean as rain and snow. Seawater contains at least a little of almost everything, but most of the solutes or dissolved materials, are made up of a surprisingly small group of ions. In fact, only six ions compose over 98% of the solids in seawater. Sodium and chloride account for about 85% of the solids, which is why seawater tastes like table salt. The salinity of the water strongly affects the organisms that live in it. Most marine organisms, for instance, will die in fresh water. Even slight changes in salinity will harm some organisms

Now, to the earth itself. Although the land iis some 4 ½ billion years old, we will start with what scientists call the Paleozoic Era. The Paleozoic Era included six periods within it. The Cambrian Period  lasted from 570 million to 500 million years ago. During this period, all life existed only in the sea. There were no vertebrates so the most advanced forms of life were snails and other small shelled organisms. The dominant species in this period were the trilobites, a now extinct species. Other creatures in this period included primitive snails, molluscs, and brachiopods. The only plants that existed were simple seaweeds which lived in the water, and lichens which grew on land.  The Ordovician period came next, lasting from 500 million to 435 million years ago. The very first vertebrates appeared in this Ordovician period, but they were only the simplest of fish. However, they would someday evolve into the biggest, most advanced species on the planet. The largest animal of this time was a mollusc that had a shell measuring about 3 metres long. The plant life in this period was the same as in the Cambrian. The Silurian Period followed lasting from 435 to 410 million years ago. One of the only great accomplishment of this period was the first breathing animal. Fossils of this scorpion have been found in Great Britain. Also, the first evidence of vascular plants (plants with tissue that carries food) comes from this period. They were very simple in nature, without even stems or leaves. Next came the Devonian Period covering the years 410 to 360 million years ago. By this time, fish had become the dominating life form. Sharks had already evolved, as well as lungfish and armored fish. This period also witnessed the birth of early forms of amphibians, and the very first insect. Additionally, the plant life really emerged. The first wooded plants appeared, along with ferns, scoring rushes, and scale trees. Fossil records show the existence of forests at this point in time. The Carboniferous Period followed during the years from 360 to 290 million years ago.  The first part of this period was sometimes called the Mississipian Period. A lot of the life here was the same as in the Devonian Period. A group of sharks called the Cestraciontes, or shell crushers, were the dominant marine species. The chief land animal was the Stegocephalia, a lizard-like amphibian, evolving from the Lungfish. The trees in this period grew larger and stronger than in the last time frame. The second part of this period is sometimes referred to as the Pennsylvanian Period. This part was very important, because the first reptiles evolved. These first reptiles lived entirely on land. Other species arriving at this time were spiders, snails, scorpions and cockroaches. A dragonfly with a wingspan of 74 cm, was the largest insect that ever evolved. The largest trees were the scale trees, which grew 1.8 metres in diameter and 30 metres high, along with the first true conifers.  The Permian Age concluded the Paleozoic Era between 290 and 240 million years ago. A prominent event of this period was that the marine animals that once dominated the planet were starting to fall back, with reptiles taking over. Since this was the last period before the dinosaurs, the reptiles were evolving fast and strong. Another very important event was the appearance of a specific reptile called the Theriodontia. Theriodontia were the ancestors of all mammals. By this time, life on Earth had pretty much taken off, and was preparing for the rule of the giant lizards called dinosaurs. The Mesozoic Era followed beginning with the Triassic Era between 240 and 205 million years ago. Probably the most important thing that happened in this period was the appearance of the dinosaurs. Triassic dinosaurs were small creatures that ran on their hind feet and seldom grew over 15 feet high. In the waters, the Ichthyosaurs began to appear, and a group of flying reptiles, called the Pterosaurs, began their rule over the sky. Another very important stage of development was the evolution of the first mammals. They were small and resembled lizards, but, even though the inferior race of the time, they possessed something that would one day allow them to rule the planet. Also in the sea, the first ancestors of modern bony fishes, the Teleostei, appeared. The vegetation was made up of evergreens, ginkgoes, conifers and palms.  Next came the famous Jurassic Era lasting from 205 million to 138 million years ago. The dinosaurs continued to evolve into very diverse species. The Sauropods appeared, which included dinosaurs such as Apatosaurus and Brachiosaurus. The carnivorous dinosaur of the time was Allosaurus, and Stegosaurus led the armoured dinosaurs. Of the Pterosaurs, the Pterodactyl appeared, which could have a wingspan of up to 1.2 metres during this period. The very first bird, called an Archaeopteryx, evolved. It looked liked a dinosaur with feathers, and was probably unable to fly, just glide. The marine life diversified as well. There were such animals as the Plesiosaurs, which looked like sauropods with flippers, the Ichthyosauria, which looked somewhat like dolphins, and early crocodiles. The mammals had become more popular, but none were any larger than dogs. Some of the insects appearing were moths, flies, beetles, grasshoppers, and termites, while the shellfish evolving were lobsters, shrimp, and ammonites. The vegetation was dominated by Cyads. The climate in the whole of the Earth was warm and mild.  The final age in the Mesozoic Era was known as the Cretaceous Age, which lasted from 138 million to 65 million years ago.  During this age the dinosaurs were still the dominating form of life. All the types of dinosaurs that abounded in the Jurassic Period thrived in this period also, including the newly evolved horned dinosaurs. The largest of the pterodactyls of this time had a wingspan of 15 metres. On a much smaller scale than the dinosaurs, but still important, were the first snakes and lizards. Many other types of birds appeared, and even though they were more modern than the Archaeopteryx, most of them were still unable to fly. The mammals of this period included the first marsupials, and the first crabs also appeared in the sea. A very important advance in the plant kingdom was the evolution of the deciduous trees, and a lot of tree species we know today first arrived during that time. Suddenly, at the end of this period, all the dinosaurs on Earth swiftly and mysteriously disappeared.  The reason for this is under scientific debate. The Cenozoic Era came next, beginning with the Tertiary Age lasting from 65 million until 1.6 million years ago. The two periods in the Cenozoic Era, consisting of 2 periods, are divided into epochs because we know so much about them. The first epoch in the Tertiary Period is the Paleocene. it lasted from 65 million to 55 million years ago. In this time, mammals were just starting to evolve. They were all small, with none being any bigger than a modern bear, and not very smart. Even though there were seven groups of mammals in the Paleocene, only four have survived until present day-the marsupials, the insectivores, the primates, and the rodents. The Eocene Epoch lasted from 55 million to 38 million years ago. In this epoch, the ancestors of such animals as the horse, rhinoceros, camel, rodent, and monkey evolved, but they were all small and primitive. Also, the first aquatic mammals, the ancestors of whales, appeared, along with modern birds such as eagles, pelicans, quail, and vultures. The next epoch was the Miocene. In this epoch, something happened that would change the development of mammals forever. The first grasses appeared. This brought with it the appearance of grazing animals such as horses, camels, and rhinoceroses, which became very common. The Mastodon also evolved, along with a gorilla-like ape called Dryopithecus. Carnivores such as cats and wolflike dogs were also common. The Pliocene epoch is very similar to the Miocene, but is looked upon as the climax of The Age Of Mammals. It lasted from 5 million to 1.6 million years ago. Next came the Quaternary Period lasting from 1.6 million years ago until the modern day. All of the animals that we have today evolved from this period, including ourselves, the humans.

 The breaking up and formation of supercontinents appears to be cyclical through Earth's 4.6 billion year history. Pangaea, was the supercontinent that existed during the Paleozoic and Mesozoic eras about 250 million years ago, before the component continents were separated into their current configuration. The single enormous ocean which surrounded Pangaea was accordingly named Panthalassa.

The Pangaea theory is one that states that all present continents were once together and collectively known as a 'supercontinent' called a Pangaea. The word 'Pangaea' means 'all lands' in Greek, accurately defining the way the continents existed 200 million years ago before it disassembled. These split-up pieces drifted slowly apart and became the way they are today. Even now, the shape of the Earth surface is still changing, and it will be forever, as long as the mantle underneath the Earth's crust gets heated and convection currents in the magma keeps dragging the plates. There were three major phases in the break-up of Pangaea. The first phase began in the Early-Middle Jurassic about 175 Million years ago, when Pangaea began to rift from the Tethys Ocean in the east and the Pacific in the west, ultimately giving rise to the supercontinents Laurasia and Gondwana. The rifting that took place between North America and Africa produced multiple failed rifts. One rift resulted in a new ocean, the North Atlantic Ocean.  The second major phase in the break-up of Pangaea began in the early Crustaceous approximately 150–140 million years ago, when the minor supercontinent of Gondwana separated into multiple continents (Africa, South America, India, Antarctica, and Australia). About 200 million years ago the continent of Cimmeria, collided with Eurasia. However, a subduction zone was forming, as soon as Cimmeria collided. This subduction zone was called the Tethyan Trench. This trench might have subducted what is called the Tethyan mid-ocean ridge, a ridge responsible for the Tethys Ocean's expansion. It probably caused Africa, India and Australia to move northward.

The third major and final phase of the break-up of Pangaea occurred in the early Cenozoic Era’s Paleocene to Oligocene Period. Laurasia split when North America/Greenland (also called Laurentia) broke free from Eurasia, opening the Norwegian Sea about 60–55 million years ago. The Atlantic and Indian Oceans continued to expand, closing the Tethys Ocean.

The Pangaea theory was treated with much skepticsm when it was first raised. But since then, there have been much evidence to support this theory.  One prominent example of continental coastline fitting together is to fit the coastline of the West Coast of Africa with the coastline East Coast of South America. It can be seen that they fit well, like pieces of a jigsaw puzzle. This helps to prove that these continents were once joined together as one whole Pangaea and broke away to form these two land masses. Matching fossil of reptiles have been found in Africa and South America, further proving that these two continents were actually so close to each other or even joined, that reptiles could travel to and from between them easily. Identical fossil ferns have also been found in all southern continents, and also embedded in the same layer sequence, suggesting the proximity the southern continents were in millions of years ago that allowed the growing of these ferns in the same climate and soil. Geologists have discovered that the geological structures of the rocks in South West Africa and South East Brazil were distinctively identical, and the age of the rocks at these two areas was the same. This distinctive rock strata shared by the two land masses suggests that these two areas were once joined together. Coal can be found underneath the cold and dry Antarctic ice cap, though coal can only form in warm and wet conditions. This could mean that Antarctica was once together with the other continents as part of the Pangaea, and was once in a warm and humid region. Coal was formed before Antarctica drifted away to its present cold and dry climate. That is why the coal can be found buried under the thick layer of ice and snow.

When sea levels were lower during the Pleistocene ice age, greater areas of continental shelf were exposed as dry land, forming land bridges. At this time Australia-New Guinea was a single, continuous continent. Likewise the Americas and Afro-Eurasia were joined by the Bering land bridge. Other islands such as Great Britain were joined to the mainlands of their continents. At that time there were just three discrete continents: Afro-Eurasia-America, Antarctica, and Australia-New Guinea

It is here that we pick up the the state of Florida’s specific history. Geologically known as the “Florida Platform”,  Florida was the rampart which separates the the Atlantic Ocean from the Gulf of Mexico.  The platform's western edge, or Florida Escarpment, is normally defined with water depths at 300 feet which quickly drop to a depth of 10,000 feet. The emergent Florida peninsula is located on the eastern side of the platform where it lies only 3 to 4 miles from the platform's edge. On the Gulf side, the platform ends over 100 miles west where a massive cliff rises over 6000 feet from the 10,600 foot depth of the Gulf floor.  The surface landmass of the Florida Platform, or what is now known as the Florida Peninsula, is scientifically known as “Orange Island”, and dates to the Rupelian Stage of the Early Oglicene era which encompasses the years between 33.9 and 28.4 million years ago.  It was during the previous Eocene stage approximately 55.8 to 33.9 million years ago, from which the platform emerged.  Originally a carbonate bank with a shallow sea covering it, over the years numerous biological carbonates were deposited on it forming various layers. As glaciers melted causing  sea levels to rise, portions of the platform remained above water.  Scientists dubbed this Island, “Orange Island” after Orange County, FL.  With most of the sea water locked up in glaciers, until those glaciers melted, the sea levels were approximately 300 feet lower than what they are today. It is believed the basement rocks of the Florida Platform were made up of Precambrian-Cambrian igneous rocks, Ordovician-Devonian sedimentary rocks, and Triassic-Jurassic volcanic rocks. Most scientists agree that Florida's foundation separated from what is now the African Plate when the super-continent Pangea rifted apart in the Triassic and possibly pre-Middle Jurassic period. It then secured to the North American craton approximately 199.6 million years ago to 145.5 million years ago.

Approximately 25 million years ago, a world wide shift in climate began cooling the air and drying the area, and as a result, the lowering sea levels enlarged Orange Island.  Not soon after, approximately 24.8 million years ago, scientists believe animals began their migration into the Florida Peninsula. The earliest known fossils have been found in Hernando County, and date to 24.8 million years ago.  Florida’s climate was cooler and drier than today’s warm humid weather, additionally there were few flowing rivers or wetlands. Across large areas of Florida, fresh water was available only in sinkholes and limestone catchment basins.  Although dinosaurs never roamed through Florida, as the state was totally submerged when they walked the earth, many other prehistoric animals called Florida home. The list of Florida’s Prehistoric Animals and Ice Age Mammals include the American Lion, Birds, Bear-Dog, Bison, Camel, Deer, Dire Wolf, Giant Capybara, Gomphothere, Giant Armadillo, Giant Beaver, Giant Short-Faced Bear, Glyptodont, Scimitar Cat, Giant Ground Sloth, Three-Toed Horse, Prehistoric Horses, Rhino, Giant Land Tortoise, Alligator, Crocodile, Agatized Coral, Tapir, Peccary, Manatee, Dugong, Dolphin, Porpoise, Turtle, Snake, Terror Bird, Fish, and Prehistoric Sharks, to name a few. Some of these animals still thrive today in some form, however many have become extinct, unable to survive the fluctuations in temperature and water levels, as well as the evolution of man, throughout the millenia.

During part or all of a low water period, there was an apparent migration of humans across a then present land bridge across the Bering Strait to Alaska.  By way of this land bridge, or causeway (Beringia), from Asia (Siberia), human hunter-gatherers migrated to North America and kept moving on for 'greener pastures’. There is little doubt that the hunter-gatherers brought many domestic animals, some botanical species, tools, hunting implements. The Beringia land mass lasted from about 47,000 to 14,000 years ago

It is believed the first Native Americans entered the Florida Peninsula approximately 3000 years after the initial mass migration through North America, or approximately 14,000 years ago. Known as the Paleo Indian Culture, certain artifacts recovered and tested date from 26,000 to 28,000 years ago.  However, scientists find these results extremely controversial.  They generally stick with the date of human occupation as 12,000 to 14,000 years ago, until more conclusive tests can be conducted on the early artifacts.  Most Paleo-Indian settlements and activity centered around watering holes. Sinkholes and basins in the beds of modern rivers have yielded a rich trove of Paleo-Indian artifacts, including Clovis points.  One of the most prominent of these sites is The Page-Ladson Prehistory Site. A designated Florida Historic Site, the location is a deep hole in the bed of the Aucilla River between Jefferson and Taylor Counties containing stratified deposits of late Pleistocene and early Holocene animal bones and human artifacts reaching back to about 14,500 to 12,500 years before the present day.  This would have been at a low water period and Florida would have been about twice as large as it is today because the sea level would have been about 25 to 35 feet lower than today. The additional land mass would have been all of the Florida Bay and a significant part of the Gulf of Mexico.  With the rising  sea waters, the Paleo-Indian's food supply evolved from large animals as bisons, mammoths, etc. to the surviving species of rabbit, deer and marine life.

As the glaciers began retreating about 8000 BC, the climate of Florida became warmer and wetter as the sea level rose. The Paleo-Indian culture was replaced by, or evolved into, the Early Archaic culture. Sometime around 4,000 years ago (2,000 BC), a seemingly independent invention of "pottery making" happened in the Florida-Georgia area. Early Venezuelan and island pottery are both dated later. Shredded materials such as palmetto fibers, Spanish moss and other grasses were used to reinforce and hold the clay together, known as temper. This is important because if sand-fired pottery fragments are found, the site is younger than this. Weapons were made of sharks' teeth, stingray barbs, billfish bills, as well as other naturally abundant materials. Eating utensils were made from coconuts, various sized shells, bones and other materials. This time is called the "Stone Age" for most of the world, but it was the "Shell Age" for the Keys. There were no stones so shells were used for various weapons, utensils and tools. Archaeologists noted another change around 1,000 BC. The pottery became rounded and the decorations were changed. Burial grounds started to be used. Some believe this was influenced by the migration of new groups from Mexico. This is the general time period when we believe natives first permanently settled the Keys in large groups.  With an increase in population and more water available, people occupied many more locations, as evidenced by numerous artifacts. Archaeologists have learned much about the Early Archaic people of Florida from the spectacular discoveries made at Windover Pond, in Brevard County near Titusville. The site was discovered in 1982 when work began on building a road across the pond in a new housing development.  Over 100 sets of remains were found including bones of males and females of all ages. In addition to the archeological data collected on the bones, brain matter was found in the majority of remains, which were protected by the peat moss which grew naturally in the Windover Pond. As a result DNA sequencing was able to be done on those found. Stomach contents were also able to be analyzed giving scientists a direct insight into the diet of Florida’s early inhabitants. Artifacts and fabrics were also found in many of the graves, and were sent for study. 

The Early Archaic period evolved into the Middle Archaic period around 5000 BC. This is when natives began living in villages near wetlands and favored sites that were likely occupied for multiple generations.

The Late Archaic period started about 3000 BC, when Florida's climate had reached current conditions and the sea had risen close to its present level. People commonly occupied both fresh and saltwater wetlands. Large shell middens accumulated during this period. Most lived in large villages with purpose-built mounds, such as at the Horr's Island, which had the largest permanently occupied community in the Archaic period in the southeastern United States. It also has the oldest burial mound in the East, dating to about 1450 BC. People began creating fired pottery in Florida by 2000 BC. By about 500 BC, the Archaic culture, which had been fairly uniform across Florida, began to fragment into regional cultures.

The post-Archaic cultures of eastern and southern Florida developed in relative isolation. It is likely that the peoples living in those areas at the time of first European contact were direct descendants of the inhabitants of the areas in late Archaic times. The cultures of the Florida panhandle and the north and central Gulf coast of the Florida peninsula were strongly influenced by the Mississippian Culture. Continuity in cultural history further suggests that the peoples of those areas were also descended from the inhabitants of the Archaic period. In the panhandle and the northern part of the peninsula, people adopted the cultivation of maize. Its cultivation was restricted or absent among the tribes who lived south of the Timucuan-speaking people, south of a line approximately from present-day Daytona Beach, Florida to a point on or north of Tampa Bay. Peoples in southern Florida depended on the rich estuarine environment and developed a highly complex society without agriculture.

Thus began what is known as the Glades Period, lasting from approximately 750 B.C until 1500 A.D. The Glades period is divided into three periods - I, II, and III. Pottery types characterize the different periods, but there are associated types of tools. By 500 BC, the tradition of adding fibers to temper the clay was largely replaced by the addition of grit, sand, shell and limestone, much as is done today. However, they did not have high temperature kilns to glaze the pottery as potters do today.  It appears that the Indian societies were still not tightly knit enough to be classified as tribes and remained classified by anthropologists as "cultures." For example, around this 500-BC era northeast Florida was occupied by the St. Johns culture, which endured for more than 1,000 years before finally evolving into the "Timucuan" tribe just before historic times. 

Meanwhile, it was primarily the Deptford Culture with the related Weeden Island and Fort Walton cultures which, by 500 BC, had spread over most of all western and central Florida. These too, were routed by rival Georgian groups and eventually evolved into the historic Pensacola, Apalachee and Tocobaga Tribes. Later, De Soto and Narvaez during their treks through the Southeastern United States encountered these Indians in 1540 and 1528.  The Glades culture occupied south Florida, which included the Keys. The Indians who lived along the southern coasts relied more on marine and aquatic items than the more northern groups.   On the west coast from Fort Myers to Naples, the Indians of the Glades culture lived on shell mounds and were the predecessors of the Calusa Indians. A group on the southeast coast lived at the mouths of rivers and streams and was with little doubt the predecessor of the Tequesta Indians in the Miami area. The Everglades and Lake Okeechobee provided a somewhat natural barrier between the historic Calusa and Tequesta, but it is widely believed that they traveled back and forth in canoes. Before all the drainage canals were dug, the water in the Everglades was much deeper. Evidence indicates that these Indians made sea journeys using large catamaran canoes with sails.  The hydraulic head pressure of the mainland fresh water sources almost surely would have provided early natives with sufficient drinking water to support life. There are still fresh water wells, also known as, solution holes, up and down the Keys, but drainage of mainland Florida has severely lowered the fresh water level and raised the level of salt-water intrusion.  There have been four accepted archaeological surveys made in the Upper Keys: Dr. John M. Goggin in 1944-49 and the Archaeological and Historical Conservancy (AHC) in 1985, and local archaeologists Irving Eyster in 1964-5 and Duncan Mathewson in 1990 (continuing to the present). Through lack of interest, and/or funding nothing scientifically conclusive has appeared to date; however, the sites are here and identified. The 1985 AHC report is fairly comprehensive, but encompasses Key Largo only. The Florida Master Site File lists all that have been officially identified. Many local historical and architectural sites have yet been submitted. Perhaps some day they will be.  There is one village site on north Key Largo thought to date back to 1,600 BC, based upon pottery evaluations. Scattered small excavations in the Upper Keys' kitchen middens seem to indicate that they are circa 500 to 700 AD. These are usually attributed to the Matecumbe group, of which little has been scientifically established. The early Spanish travelers frequently mentioned the Matecumbes. 

The next period in Florida’s history is known as the “Historic Contact Period” which lasted from 1500 until 1750 A.D. During this period written accounts begin to appear; albeit, the writings of the the Europeans. Written accounts of Ponce de Leon, Hernando Fonteneda, and Jonathan Dickinson, among others have been translated for everyone to read. The writings are of contact made with Calusa and Tequesta mainly by the Spanish during this period; although the French and English had contact. Most agree that around the time of English ownership of Florida in 1763 the population of indigenous Florida Native Americans were either dead or had migrated to Cuba.

The period from 1750 A.D. until today is what is know as the Historic Period.  White settlers were becoming more interested in Florida. At the same time Creek Indians were being driven westward and independent bands of the Creek Nation found their way southward to Florida. The predominant mode of transportation were the many rivers that flowed southward. These Neo-Florida Indians would eventually become known as the Seminole.