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Fossilized Shark Teeth on the Internet |
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A.) UNDISTURBED FORMATION:
The Green River formation in Wyoming and the Bear Gulch region in Montana are two famous US formations. The "future fossils" were put down on the ocean floor, covered over with sediment over time, fossilized and the ocean receded and never came back. The fossils were deposited in a formation (layer, horizon or stratum) which millions of years later became exposed or near the surface due to erosion and we are now "harvesting" them. They are all MARINE fossils in "virgin", "pure", "non-reformulated" or "undisturbed" formations.
The Green River formation in Wyoming and the Bear Gulch region in Montana are two famous US formations. The "future fossils" were put down on the ocean floor, covered over with sediment over time, fossilized and the ocean receded and never came back. The fossils were deposited in a formation (layer, horizon or stratum) which millions of years later became exposed or near the surface due to erosion and we are now "harvesting" them. They are all MARINE fossils in "virgin", "pure", "non-reformulated" or "undisturbed" formations.
B.) RIVER REFORMULATED
FORMATION:
The Fossil Assemblage called the "Sharktooth Hill Local Fauna" is part of the Round Mountain Silt Formation and is located in Kern County near what is now Bakersfield, California. This Fossil Assemblage is composed of 2 layers - an older, reformulated, lower layer and a younger, undisturbed, upper layer.
17 to 15 million years ago (MYA) this area was a very shallow bay or marsh. An ancient river flowed into this bay from the recently uplifted mountains. It carried with it fossil remains of animals that died in earlier Miocene times - mostly marine but also a few land animals that died in the river. This 8-to-12 inch bone bed is compact and jumbled. The fossils bones, teeth, rock and petrified wood were scattered and dispersed from their original resting place and are sometimes piled up together.
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The upper fossil layer is a younger layer containing more complete skulls and skeletons that settled about 4 feet above the older, lower layer. This top layer is undisturbed and fossils were deposited in the shallow, saltwater bay about 13 MYA and generally lie where they came to rest from shedding or the animal's death. Complete skeletons are sometimes found in the upper layer but rarely found in the lower.
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The upper layer is a present day, relatively "undisturbed", "pure" formation whereas the lower layer is a RIVER REFORMULATED FORMATION.
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C.) OCEAN REFORMULATED FORMATION:
The Oligocene was not the greatest epoch for deposition of fossils along the Eastern Seaboard of the US. In general, the earth was colder than the later Miocene Epoch and some of the ocean water was locked up in ice sheets, primarily due to formation of the Antarctic Ice Cap. The sea levels dropped during part of that time and the coastlines receded. As a result, several species of sharks that lived during this period are not well represented in the fossil fauna of the Mid-Atlantic States. Of course, this is a generalization as there were several transgressions and regressions during the 10 million year Oligocene and Carcharocles angustidens ARE found in the interior of South Carolina.
In what was to become the present day Eastern Coast of the US, some Oligocene Epoch MARINE teeth (like C. angustidens) were laid down on the ocean floor, covered over, became fossils. The ocean receded and what was ocean floor became flat land. Sediments from erosion of higher land covered the fossil layer.
Millions of years later, the ocean transgressed this relatively flat, dry land and Miocene Epoch marine fossils (like C. megalodon teeth) were deposited in a new layer above the Oligocene fossils. The Miocene was a time of warmer global climates and higher sea levels than those in the preceeding or following epochs. As the ocean again receded more sediment from rivers covered these 2 layers. During the Mid Miocene Epoch more icebergs formed causing the ocean to recede even further. During the time this area was dry land and two things happened: (1.) LAND ANIMAL teeth, bones, etc. were laid down, covered over, became fossils. (2.) The land uplifted due to continental plate tectonics. The uplifting of the Appalachian Mountains occurred during this Epoch only 250 miles (155 Km) from the present coastline of North Carolina.
So at that time there was an Oligocene MARINE Formation, let's say 80 feet down then 20 feet of dirt with few fossils and then 60 feet down a Miocene MARINE Formation, then 20 feet of sediment, then 40 feet down an Miocene LAND Formation full of mices, rats, porcupines, guinea pigs, horses, hogs, camels, deer, lizards, turtles, snakes, alligators, birds, bats, mastodons, raccoons, weasels, cats, doglike carnivores and rhino fossils. Over the years dirt and sediment from the erosion process covered this last layer.
Now comes the interesting part:
During the Late Miocene, the icebergs melted again, the ocean came back in and in the process, eroded the HIGH LAND to the point that all the fossils FROM ALL 3 FORMATIONS are washed out and settled together at the bottom of this eroding cliff. They were, in time, covered over by sediment, the ocean receded yet again and now (1 million years later - present time) the COMBINED fossils are becoming exposed and we are now "harvesting" them. We find shark teeth alongside horse teeth!! The Hawthorn Formation which runs along the Eastern Coastal region of the US from Florida to North Carolina, is an OCEAN REFORMULATED FORMATION.
In what was to become the present day Eastern Coast of the US, some Oligocene Epoch MARINE teeth (like C. angustidens) were laid down on the ocean floor, covered over, became fossils. The ocean receded and what was ocean floor became flat land. Sediments from erosion of higher land covered the fossil layer.
Millions of years later, the ocean transgressed this relatively flat, dry land and Miocene Epoch marine fossils (like C. megalodon teeth) were deposited in a new layer above the Oligocene fossils. The Miocene was a time of warmer global climates and higher sea levels than those in the preceeding or following epochs. As the ocean again receded more sediment from rivers covered these 2 layers. During the Mid Miocene Epoch more icebergs formed causing the ocean to recede even further. During the time this area was dry land and two things happened: (1.) LAND ANIMAL teeth, bones, etc. were laid down, covered over, became fossils. (2.) The land uplifted due to continental plate tectonics. The uplifting of the Appalachian Mountains occurred during this Epoch only 250 miles (155 Km) from the present coastline of North Carolina.
So at that time there was an Oligocene MARINE Formation, let's say 80 feet down then 20 feet of dirt with few fossils and then 60 feet down a Miocene MARINE Formation, then 20 feet of sediment, then 40 feet down an Miocene LAND Formation full of mices, rats, porcupines, guinea pigs, horses, hogs, camels, deer, lizards, turtles, snakes, alligators, birds, bats, mastodons, raccoons, weasels, cats, doglike carnivores and rhino fossils. Over the years dirt and sediment from the erosion process covered this last layer.
Now comes the interesting part:
During the Late Miocene, the icebergs melted again, the ocean came back in and in the process, eroded the HIGH LAND to the point that all the fossils FROM ALL 3 FORMATIONS are washed out and settled together at the bottom of this eroding cliff. They were, in time, covered over by sediment, the ocean receded yet again and now (1 million years later - present time) the COMBINED fossils are becoming exposed and we are now "harvesting" them. We find shark teeth alongside horse teeth!! The Hawthorn Formation which runs along the Eastern Coastal region of the US from Florida to North Carolina, is an OCEAN REFORMULATED FORMATION.
Important things to remember:
1.) A formation reformulated out of other formations will contain fossils from earlier times, but NEVER from later times. A "pure" formation will only contain fossils from the time period in which it was formed. The Hawthorn is a MIOCENE FORMATION (meaning formed during the Miocene Epoch) which contains Oligocene Marine, Miocene Marine and Miocene Land fossils. Stated another way, Reformulated Formations were formed LATER in Geologic Time than any of their constituents.
2.) In most cases and with heavy sedimentation, Reformulated Formations are found DEEPER in the earth than any of the formations from which they are made. To the casual observer this would indicate that they are EARLIER formations, but this is not the case.
If this were not complicated enough:
Many North and South Carolina formations are
accessible from land sites. The Eocene Castle Hayne Formation and the
Eocene/Oligocene Chandler Bridge Formation are both exposed in rock quarries and
during digging for building foundations. Several South Carolina rivers
have also cut through these formations and moved these fossils downstream to
pile up together on sand and gravel bars. Some of these rivers also cut
through the reformulated Hawthorn Formation. The end result is that several "pure" formations and at least one reformulated formations have been combined into one new "formation in progress". When picking fossils off the riverbed of the Cooper River in South Carolina, the diver has no idea of the geologic age of the FORMATION THE FOSSIL ORIGINATED IN. It could be Upper Cretaceous, Palaeocene, Eocene, Oligocene, Miocene, Pliocene or Pleistocene!! Hawthorn Formation fossils, having survived the Ocean Reformulation in the Miocene are now going through a new phase of being River Reformulated. In effect these fossils are being re-reformulated.
Another section of the Hawthorn Formation is presently being ocean re-reformulated by the Atlantic Ocean a few hundred feet off the coast of Topsail Island, North Carolina. In another area of North Carolina the Tar and Pamlico Rivers are now in the process of reformulating the Pungo River, Yorktown, Chowan and Croatan Formations into one new formation - presently unnamed.
NOTES:
1.) During Ocean Reformulation shark teeth were (are) subjected to wave action, tidal currents and scouring by sand, rocks, shells and other fossils. Serrations, root ears, blade edges, blade tips and enamel shine were degraded. A modern day example of this are the teeth that are found on Venice Beach, FL.
2.) During River Reformulation in rivers with fast moving currents, the teeth are tumbled end-over-end along the river bed. This causes no end of problems like worn serrations, root ears and blade tips. If the teeth encounter large rocks in their journey, the blade edges, root ears and tips can be nicked, chipped and rounded.
3.) In the case of Cooper River teeth, the fossils that originated in the Hawthorn Formation and survived the Ocean Reformulation are now being further degraded by the River Reformulation.
4.) The AGE OF A REFORMULATED FORMATION is almost impossible to determine. This age can be inferred from the formation's position relative to known formations, but as we have seen, this does not always work. Microfossils or "Index Fossils" which paleontologists depend on to date fossils layers, are almost never present because of their light weight, small size and the dispersion of these fossils during the reformulation process. Microfossils that are present might have come from any of the ages that comprise the new layer. The AGE OF THE FOSSILS can be directly inferred from knowledge of their presence in other, well dated formations.
5.) Many people use the word "Reworked" instead of "Reformulated". We do not like this word because it implies that the fossils or formation was originally "Worked". We much prefer the concept of a formation being "Formed" and "Reformed".
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