The Carolina Bays can be shown to be mathematically elliptical by fitting them with ellipses using the least squares method. This fact imposes rigorous criteria for any hypothesis about the origin of the bays because the hypothesis needs to explain the physical mechanisms that produce the mathematically elliptical basins.
The Carolina Bays are shallow elliptical basins with raised rims that are oriented toward the Great Lakes. Many hypotheses have been proposed to explain their origin. One hypothesis with wide support from geologists proposes that the basins were created by wave action from prevailing winds on ponded water. Another hypothesis proposes that the Carolina Bays originated as thermokarst lakes formed from sinkholes in permafrost by ice-melt processes. A less popular hypothesis proposes that the Carolina Bays originated as inclined conical cavities from secondary impacts of glacier ice chunks ejected by a comet impact on the Laurentide Ice Sheet.
The most important step for developing a scientific hypothesis is to learn the attributes of the subject. A valid hypothesis cannot be obtained without a clear definition of the subject. A hypothesis consists of ideas that explain the attributes of the subject. The final step is to verify the ideas to see where they fail, and modify the hypothesis with new ideas that explain the attributes of the subject better.
The Carolina Bays have four main attributes. They have oval or elliptical geometry. They have uniform orientation. The basins have raised rims, and they frequently overlap while maintaining their characteristic geometry. A valid hypothesis must be able to explain how these four attributes originated from the action of known physical mechanisms of natural events.
The first step in evaluating the attributes of the Carolina Bays must be to clarify if the bays are oval or elliptical. If the Carolina Bays are mathematically elliptical, this will require any hypothesis to explain how these elliptical features were created. Then, if the hypothesis cannot explain the physical forces that created the elliptical basins, the hypothesis must be discarded because it cannot explain the attributes of the bays. A Python program to fit ellipses to the Carolina Bays by the least squares method is a useful tool for evaluating the geometry of the bays. This program is open-source software available in GitHub.
We are going to use the Python program to evaluate this cluster of Carolina Bays near Bowmore, North Carolina. We select points along the perimeter of each basin and record the Cartesian coordinates in a text file. The Python program processes the text file and fits an ellipse to the points using the least squares method. The program outputs a graph of an ellipse through the points and a percentage that indicates the deviation of the points from the ellipse. For Carolina Bays, the fitting error is usually less than 3 percent.
Applying the program to other Carolina Bays in the same cluster, we get similar results. The deviation from a perfect ellipse is less than 2 percent in these four cases. The degree of precision for these geological features is remarkable considering that the basins have been subject to wind and water erosion for thousands of years, and in the last few hundred years they have been modified by human urbanization and farming.
There are thousands of examples that can be used to establish that the basic geometry of the Carolina Bays is mathematically elliptical and not just oval. Even basins that have been heavily eroded retain some of the characteristic features.
The book Planetary Surface Processes published in 2011 by Professor Jay Melosh classifies the Carolina Bays as thermokarst lakes that are often aligned with the prevailing wind. The Carolina Bays are mentioned in the context of active thaw lakes that are found in northern Alaska, Yukon Territory, and northern Russia. These thaw lakes are formed during periods of climatic warming when melting permafrost causes the land to sag and create sinkholes that fill with melt water.
Looking at the lakes in northern Alaska, we have to ask: Do these lakes have the same physical attributes as the Carolina Bays? They are aligned, but they don't have the geometry and the raised rims typical of the bays.
We can actually test the geometry of these lakes by selecting points along the perimeter and processing the points with the Python program.
We are going to examine this cluster of four adjacent lakes. The perimeter of this lake differs from an ellipse by 21.49 percent. We can contrast this with the Carolina Bays that had a fitting error of less than 3 percent.
This Alaskan lake lacks the symmetry of the Carolina Bays and it has a fitting error of 12 percent. This peanut-shaped thermokarst lake differs from an ellipse by 45.2 percent. It is not at all similar to a Carolina Bay. Notice the extreme elongation of the ellipse. The lake has a length almost 5 times as big as its width. Carolina Bays do not have such elongated shapes. Most bays seldom exceed a length-to-width ratio of 2 to 1. This Alaskan lake has a fitting error of 13.1 percent. The difference from an ellipse is still too great compared to the fitting errors of the Carolina Bays.
The disparities that seem obvious by visual inspection are confirmed by the mathematical analysis. The geometrical characteristics of thermokarst lakes in Alaska differ significantly from those of the Carolina Bays.
We can conclude that the book by Prof. Melosh is wrong about the Carolina Bays. The Carolina Bays could not have originated from thermokarst lakes because these lakes do not have the same elliptical characteristics as the bays. In addition, North and South Carolina never had permafrost even during the Last Glacial Maximum, so the bays cannot be related to ice melt processes.
After using precise measurements, we can say with certainty that the Carolina bays are not oval. They are elliptical, and this means that any hypothesis about the origin of the Carolina Bays must explain how this particular geometry is achieved. A hypothesis proposing that the Carolina Bays were created by wave action from prevailing winds on ponded water must explain the precise mechanism by which eolian and lacustrine forces can consistently create mathematically elliptical basins. The hypothesis would gain some credibility from experiments demonstrating this effect.
Oblique secondary impacts that produce inclined conical cavities seem to be the best explanation for the Carolina Bays, but this is not being considered by mainstream geology at this time because it requires the occurrence of an extraterrestrial impact on an ice sheet in the Earth's recent past and no crater for such an impact has been found yet. However, experimental impacts of ice projectiles on viscous targets produce basins analogous to the Carolina Bays, including the characteristic overlaps.
