The Glacier Ice Impact Hypothesis proposes that the Carolina Bays were created by oblique secondary impacts of glacier ice boulders ejected by an extraterrestrial impact on the Laurentide Ice Sheet.
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Predictions of the Glacier Ice Impact Hypothesis. Scientific predictions are not made with a crystal ball. They are derived from the mathematical and logical consequences of a hypothesis. The Glacier Ice Impact Hypothesis originated from the observation that well-preserved Carolina Bays are perfect ellipses. This is easy to verify using LiDAR images, a laser ranging technology that eliminates the interference of vegetation and provides clearer images than those obtained by satellite or aerial views.
Nebraska has similar elliptical features called rainwater basins that are oriented in a southwest direction, instead of the southeast orientation of the Carolina Bays. The major axes of the Nebraska Rainwater Basins and the Carolina Bays intersect by the Great Lakes in Saginaw Bay. This is presumed to be the point of origin of the material that created the basins and the bays.
The paper entitled "A model for the geomorphology of the Carolina Bays", published in 2017 in the peer-reviewed journal Geomorphology proposed that the elliptical geometry of the Carolina Bays and the Nebraska Rainwater Basins could be explained if these geological features originated as inclined conical cavities because ellipses are conic sections.
The paper introduced the Glacier Ice Impact Hypothesis, which proposed that an extraterrestrial impact on the Laurentide Ice Sheet ejected glacier ice boulders in ballistic trajectories and that their oblique secondary impacts liquefied the ground and created inclined conical cavities that became shallow elliptical bays by viscous relaxation.
The elliptical geometry of the Carolina Bays was the starting point for applying the mathematical methods of physics to deduce information about the proposed extraterrestrial impact and its icy ejecta. The bay geometry corresponds to launch angles. Ballistic equations determine projectile trajectories. Yield equations correlate bay size to projectile size, and the energy to create all the bays provides information about the magnitude of the extraterrestrial impact.
By using various distances and angles, the ballistic equations indicate that the glacier ice boulders in the ejecta curtain needed speeds of 3 to 4 kilometers per second to reach Nebraska and the East Coast. In addition, the ballistic equations show that the ice boulders had sub-orbital trajectories in the vacuum of space from 150 to 368 kilometers above the surface of the earth, which is well above the 100-kilometer limit of the atmosphere.
Power law scaling equations implemented by Prof. Jay Melosh and Ross Beyer relating projectile size to crater diameter can be used to estimate the size and energy of the ice boulders that made the Carolina Bays. A Carolina Bay with a diameter of one kilometer requires an ice projectile with a diameter of 180 meters and energy of 3 megatons of TNT. Using the law of conservation of energy, it is possible to calculate the energy of the extraterrestrial impact from the energy required to form all the bays.
The Glacier Ice Impact Hypothesis explains all the features of the Carolina Bays and Nebraska Rainwater Basins, including their elliptical shape, radial orientation, raised rims, undisturbed stratigraphy, absence of shock metamorphism, overlapping bays and the occurrence of bays only in unconsolidated ground.
The Glacier Ice impact Hypothesis predicts that the raised rims of the Carolina bays will have inverted stratigraphy characteristic of impacts. This is the first prediction. Inverted stratigraphy is created in the rim of an impact crater when the flanges produced by the penetration of the projectile fold over the existing landscape. Inverted stratigraphy can be detected by examining at least three sections of a core sample in the rim. Proceeding from the top down, the surface layer contains the youngest material that accretes by ordinary eolian and sedimentary processes. Immediately below the youngest layer there is a layer of older material that was excavated and flipped over during the formation of the elevated rim. Below the layer of older material is a layer of young material that was the original surface of the terrain before the impact cavity formed. Deeper layers contain progressively older material.
When I made the prediction of inverted stratigraphy for the Carolina Bays in 2017, I was not aware of any such cases. One year after my publication, my neighbor Adam Glass who was very interested in the Carolina Bays, brought to my attention a paper published five years earlier that had reported inverted stratigraphy.
Ted Bunch and 17 co-authors published a paper in 2012 that shows the dates obtained at different depths of a single test location in the rim of a Carolina Bay near Blackville, South Carolina. The samples for optically stimulated luminescence were taken at 107, 152, and 183 centimeters below the surface. The layer at 107 centimeters had an age of 11.5 thousand years. The layer at 152 centimeters had a date of 18.5 thousand years, and the layer at 183 centimeters had a date of 12.9 thousand years. This clearly shows inverted stratigraphy since an older layer is sandwiched between two relatively younger layers.
In 2012, the rims of the Carolina Bays were thought to be eolian in origin, that is, created by wind-blown sand, so the layer showing the inversion was excluded as explained in the paper: QUOTE: The two dates at 107 and 183 centimeters below the surface were used to generate an age-depth model, excluding the sample at 152 centimeters because of the large magnitude of the age reversal, that is, older sediments lying stratigraphically higher than younger sediments. END QUOTE. As far as I know, this is the only publication that has done such detailed analysis at different depths of a Carolina Bay rim. This paper illustrates why it is important to report all data, even data that seems anomalous. The date that was considered abnormal and was discarded by Ted Bunch and his colleagues has been very valuable for supporting the impact origin of the Carolina Bays.
The second prediction made by the Glacier Ice Impact Hypothesis was that clasts carried by the glacier ice projectiles might be found at the bottom of some of the bays where the ice boulders stopped. Clasts are just broken pieces of rocks and finding them within the Carolina Bays is a lot harder than finding inverted stratigraphy in the rims, which are more accessible.
On August 16th, 2019, George Howard, the founder of Restoration Systems, LLC in North Carolina, organized the exploration of Arabia Bay. This LiDAR image of Arabia Bay shows the well-defined rims that have defied erosion by wind and water for thousands of years. Arabia bay is relatively small with a width of 265 meters and a length of 390 meters. The ice projectile that made this bay had a diameter of about 75 meters and its impact energy was equivalent to 278 kilotons of TNT.
This was the first time that the apex of a Carolina Bay where the glacier ice boulder is thought to have stopped was explored. In this photograph, George Howard is collecting samples along the wall of a trench. The samples are being processed by Chris Cottrell and his science students.
The Laurentide Ice Sheet varied in thickness. In some places, like Hudson Bay, the ice was three or four kilometers thick during the Last Glacial Maximum, but in the Great Lakes region the ice was approximately one to two kilometers thick. The margins of the ice sheet advanced and retreated several times during the ice age.
If we are going to be looking within the Carolina Bays for clasts brought by the glacier ice boulders, it is important to notice that the top of a glacier has clean ice, but the bottom of the glacier accumulates dust and rock particles when the ice scrapes and flows over the terrain. When a glacier melts, it leaves mounds of clasts and glacial till called moraines as shown in the inset. Glaciologists use moraines to study the coverage and movement of glaciers that melted thousands of years ago.
A Carolina Bay made by a piece of ice that came from the top of the glacier would probably have no clasts or glacial till. A Carolina Bay made by a piece of ice from the bottom of the glacier would be more likely to have rocky material from the terrain where the glacier originated. A Carolina Bay made by a large piece of glacier ice would be more likely to contain stony clasts because the ice piece represents a greater cross-section of the glacier. This means that the search for glacier clasts may be more successful in large Carolina Bays made by big chunks of glacier ice.
This large Carolina Bay is located 33 kilometers southwest of Fayetteville, North Carolina. Like all well-preserved bays, it geometry is precisely elliptical with a width of 2,100 meters and a length of 4,160 meters. The width-to-length ratio of the ellipse can be used to calculate that the angle of impact was 30 degrees.
The bay is so large that the Mall in Washington, D.C. from the Lincoln memorial to the Capitol of the United States could fit inside the bay. The equations correlating crater size to projectile diameter estimate that the ice boulder that made this bay had a diameter of 1,180 meters and energy of 1,250 Megatons. But using the ratio of projectile size to cavity length from tabletop experiments we estimate that the size of the ice boulder was about 800 meters. In any case, the ice boulder had a diameter in the range of one kilometer, which might be a representative sample of the one- or two-kilometer thick Laurentide Ice Sheet. The size of the ice boulder also represents the size of the area that would need to be explored to find clasts within the bay.
Professor Peter Schultz from Brown University has conducted numerous experiments where high-speed projectiles strike an ice sheet. The experiments always show pieces of ice of various sizes being ejected by the impact. The sizes of the Carolina Bays indicate that colossal ice chunks with a diameter of one kilometer would have been part of the ejecta curtain resulting from the impact of a meteorite on the Laurentide Ice Sheet.
My tabletop experiments have demonstrated that oblique impacts of ice projectiles on a viscous target produce inclined conical cavities that are elliptical when viewed from above. These experiments are easy to replicate. The experimental results can be measured to determine the size of the cavity relative to the projectile size. The proportions can be used to analyze the Carolina Bays, assuming that the results scale-up.
The inclined conical cavities become shallow elliptical depressions by viscous relaxation. On inclined terrain, mud flows into the cavity and creates deformed bays. This particular experiment demonstrates the distortion resulting from the inclined terrain, but it also shows that ice floats on the surface of the liquefied soil. This means that the ice boulders that made the Carolina Bays may have ended closer to the surface than the apex calculated for the conical cavity. And, if the glacier ice projectiles floated, the clasts and glacial till would be closer to the surface after the ice melted. It will still be necessary to dig several hundred meters below the surface to find clasts and glacial till brought by the large glacier ice boulders. For a Carolina Bay made by an 800 meter glacier ice chunk, it might be necessary to get samples from more than 600 meters below the surface, which would require some sophisticated drilling equipment.
The second prediction made by the Glacier Ice Impact Hypothesis is still under investigation. This presentation has looked at the properties of glaciers to formulate an approach for exploring the Carolina Bays and find clasts that might have been carried by glacier ice boulders ejected by an extraterrestrial impact on the Laurentide Ice Sheet. The exploration of Arabia Bay is the first attempt to find such evidence and it is still being processed. Thus far, the first prediction of inverted stratigraphy has been confirmed, and the second prediction is being studied. Finding glacial clasts within the Carolina Bays would firmly establish the Glacier Ice Impact Hypothesis as an explanation for the origin of the Carolina Bays and the Nebraska Rainwater Basins. Stay tuned.
