Antonio Zamora Podcast
Antonio Zamora Podcast

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Beavers and Carolina Bays

Examination of a biological explanation for the formation of the Carolina Bays that shows the difficulty of falsifying a scientific hypothesis. How does a hypothesis become mainstream and what does it take to disprove a hypothesis?

Beavers and Carolina Bays
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Beavers and Carolina Bays. Among the many mechanisms suggested for the formation of the Carolina Bays is a hypothesis by a librarian at the University of Georgia named Bob Kobres who proposed that the bays originated from ponds made by giant beavers that lived during the Pleistocene. The passage of a bolide radiated enough energy to produce violent steam explosions in the beaver ponds and other wet spots, and the pressure pulse from the blasts gave the bays their unusually regular shape.

I hesitated before making this video because the hypothesis that the beavers contributed to the formation of the Carolina Bays seemed preposterous, but on further investigation some of the ideas had merit. In addition, the hypothesis is a scientific hypothesis because it is falsifiable. Thus, if we can prove that beaver ponds could not have become Carolina Bays, then we can conclude that the hypothesis is false. But as you will see, this is not an easy task.

The Carolina Bays are shallow elliptical depressions with raised sandy rims that are uniformly orientated toward the southeast. The bays range in size from a few hundred meters to several kilometers in size. Some bays overlap while keeping their elliptical shape.

Images obtained using LiDAR, a laser ranging technology, reveal Carolina Bays that are invisible in satellite images. These bays near Midlothian, which is a suburb of Richmond, Virginia, show roads and neighborhoods that have been built on top of the bays. Although many bays have been drained for farming and urban development, some have been converted into parks for boating, picnicking and swimming, like this bay in Jones Lake State Park, North Carolina. The water is tea-colored and few fish species are present due to the water's acidity.

The sand rims of the bays that look elevated in the LiDAR images are just unremarkable sandy areas in the forest when viewed from ground level. This is why the Carolina Bays did not receive great attention until the introduction of aerial photography in the 1930s. Many ideas have been suggested for the origin of the Carolina Bays. Some have been published in peer-reviewed journals, while others have been published in books, magazines, newspapers and other media.

The origin of the Carolina Bays has always been controversial because it has been difficult to get a consensus about how they formed. The theories of their formation have included celestial, terrestrial, and biological mechanisms.

Several scientists have proposed that the Carolina Bays are the scars of a meteor swarm from pieces of a comet that disintegrated during its passage through the Earth's atmosphere. Others have proposed that gyroscopic eddies in water currents gave the bays their elliptical structure. Some have proposed that the bays were carved by artesian springs and modified by sand carried by the wind. And then there is the suggestion that the bays originated from fish nests made by giant schools of fish waving their fins in unison. Incredible! But this hypothesis was published in a peer-reviewed journal.

It turns out that behind every idea that seems absurd there is some logical explanation. Here is an image of fish nests in shallow water. The fish nest depressions have raised sandy rims and some of the nests overlap. Could some of these become Carolina Bays if they were larger? How can you prove that this is not possible? It is not so easy.

Let us get back to the beavers and the Carolina Bays. Bob Kobres says that Ice Age beavers could have created vast expanses of ponds and wetlands that exploded into steam when a comet arrived. The radiant energy from the incoming bolide produced violent steam explosions in the beaver ponds and other wet spots, and the pressure pulse from the blasts gave the bays their unusually regular shape. The giant beavers became extinct along with the other megafauna at the onset of the Younger Dryas cooling event.

The giant beavers that lived during the Pleistocene were up to‭ ‬2.2‭ ‬meters long, or about 7 feet. Their height was about one meter or 3 feet, and they weighed as much as a black bear, so in theory they could have constructed much bigger ponds than modern beavers.

Beavers can change a landscape dramatically. Twenty-five pairs of North American beavers were introduced to Tierra del Fuego island in 1946 with the aim of developing a fur industry. The forests of Tierra del Fuego are not adapted to the habits of beavers. When beavers cut a tree it dies because it does not regenerate branches from the roots like the trees in North America.

This map shows the locations of beaver colonies in Tierra del Fuego at the tip of South America. With plenty of food sources and no natural predators, the beavers proliferated rapidly and caused the largest landscape-level alteration in subantarctic forests since the last ice age.

When humans introduce new species into non-native habitats, there are always adverse environmental effects. There are many examples, such as the goats in the Galapagos Islands, the Burmese pythons in Florida, rabbits in Australia, and beavers in South America. When the damage to the environment is noticed, eradication programs of the invasive species try to restore the balance. Sometimes governments offer bounties to encourage private citizens to participate in the eradication efforts. This photograph shows a series of beaver ponds along a creek in Tierra del Fuego. The land along the banks of the creek has been denuded of vegetation. A satellite view shows beaver ponds neatly spaced along a stream. Each pond sustains a family of beavers.

The Tidal Basin in Washington, D.C. is a showcase for the Jefferson Memorial and the cherry trees that bring thousands of tourists to the nation's capital every spring. The cherry trees along the perimeter of the tidal basin are really spectacular when they are blooming.

So, whenever something threatens the cherry trees, the authorities take quick action. This article in the Washington Post says that a beaver cut down four cherry trees, five white cedars, and gnawed the trunks of four more large cherry trees. The Park Service quickly got rid of the beaver in spite of the beaver's evasive maneuvers.

This is a LiDAR image of the Carolina Bays near Fayetteville, North Carolina. Some of the bays have a length of 4 kilometers. Is it possible that all these bays originated from beaver ponds? How many beavers does it take to make all those Carolina Bays? Will there be any room left for the mastodons, camels, mammoths, lions, giant armadillos, and the saber-toothed tigers? Clearly, ridiculing an idea is a logical fallacy and it is not the way to falsify a hypothesis. We can put the burden of proof on the originator of the hypothesis to show that the beavers can cover with ponds all the surface of the East Coast of the United States and that the heat of a bolide can create steam explosions that produce elliptical bays. But we really don't have enough information about the beavers or the bolide to falsify the hypothesis. All that we have done is shifted the burden of proof to the originator of the hypothesis.

Analysis of LiDAR images shows that well-preserved Carolina Bays and Nebraska rainwater basins are perfect ellipses with width-to-length ratios of approximately 0.58. This implies that the features in the East Coast and those in Nebraska may have formed by similar mechanisms and that their origin is related.

In 2010, Davias and Gilbride used great circle trajectories adjusted for the Coriolis effect to calculate the convergence point of the Carolina Bays and Nebraska Rainwater Basins at Saginaw Bay in Michigan. The convergence point indicates the location where an asteroid or comet could have impacted the Earth. The fact that there is no recognizable crater in Saginaw Bay suggests that the terrain was covered with a layer of ice that protected the surface and prevented the formation of a typical extraterrestrial impact crater. The ice ejected from the impact on an ice sheet would have produced secondary impacts that created the bays.

The creation of elliptical structures is based in geometry and the laws of physics. From the Ancient Greeks we know that ellipses are conic sections. A cone cut at an angle inclined to its central axis produces an elliptical surface. From physics we know that a projectile traveling in a viscous medium produces a conical shock wave. Thus, an oblique impact on a viscous surface will produce an inclined conical cavity, which viewed from above will have an elliptical shape. This mechanism will work in Nebraska as well as in the East Coast.

The lower images show an experimental impact of an ice projectile on a mixture of pottery clay and sand. This physical model demonstrates that oblique impacts on a viscous surface can produce inclined conical cavities that are elliptical when viewed from above. Is the idea of impacts more plausible than the one about the beaver ponds?

A scientific hypothesis is adopted as mainstream when it explains the physical observations and it has broad support from the scientific community. Without support from the community, a good idea can languish for many years before its significance is recognized.

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