The Younger Dryas cataclysm was marked by a megafaunal extinction that eliminated the rich diversity of large animals that populated North America. The Clovis people who lived in North America along with these animals also perished, but their perspective of this momentous event is generally ignored.
Most discussions about the Younger Dryas mention the megafaunal extinction that accompanied this cooling event. The rich diversity of large animals that populated North America that included mammoths, mastodons, ground sloths, lions, giant armadillos and saber-toothed tigers disappeared in a geological instant. These animals had survived previous glacial cycles, so their disappearance cannot be blamed on climate alone.
Toward the end of the Pleistocene Epoch, about 13,000 years ago, the Earth was starting to come out of an ice age, but the climate suddenly became very cold. This sudden return to glacial conditions is called the Younger Dryas cooling event, and it lasted about 1200 years.
The cooling event was caused by the melting of the Laurentide Ice Sheet, which released vast amounts of freshwater into the salty North Atlantic Ocean and disrupted the thermohaline circulation pattern that had brought warm water from the tropics to the North Atlantic. But what caused the ice to melt so suddenly?
One of the clues that we have about the Younger Dryas is a landscape of elliptical basins on the East Coast of the United States and in Nebraska that are oriented toward the Great Lakes. These elliptical features are the result of powerful secondary impacts of glacier ice chunks that were ejected by a comet impact on the ice sheet that covered North America 12,900 years ago. Some experts disagree that there was ever an extraterrestrial impact in our recent past, but the mathematically elliptical Carolina Bays and the Nebraska Basins cannot be explained by ice melt processes or by wind and water mechanisms. These elliptical basins could have been made by the ballistic sedimentation of an icy ejecta curtain with energy equivalent to many megatons of TNT per square kilometer over an extensive area.
The onset of the Younger Dryas is marked by an unusual increase of platinum, which is an element usually associated with extraterrestrial material. There is also a wide distribution of impact proxies, such as metallic microspherules and nanodiamonds that could only have formed at high temperatures during an impact event.
The flat plains of North America did not have many rocky outcrops with caves that could have been used for shelter by the Clovis people. The weather at the end of the Pleistocene was very cold, and humans would have had to build shelters that could be transported easily to support the nomadic lifestyle that was necessary to follow the seasonal migration of animals and find plant foods as they ripened. The sound of stones clashing could always be heard when someone was knapping flint arrow heads, spear points, or scrapers for processing hides and preparing spears and shafts for arrows. Tending fires was also an important task for cooking food and to provide warmth. The activities around the camp involved making tools for hunting, processing meats and plant foods, and making clothing and shelter from animal skins and natural fibers.
The Clovis camps were close to rivers and lakes that offered the opportunity of catching fish by spearing them or by trapping them with nets. These bodies of water would also attract wild life that could be hunted.
The Clovis people followed herds of animals and used distinctive fluted spear points to hunt megafauna like mammoths and bison, as well as smaller animals. The members of the hunting group had to coordinate their activities to guide prey animals into dead ends or use surprise attacks including fire and smoke to panic animals into ambushes. Once a large animal was killed, the hunters had to butcher the animal and carry the parts back to the camp while avoiding fierce predators and scavengers. There was safety in numbers. A large hunting party could be more successful hunting and returning with food for the camp.
At the end of the day, everyone gathered by the fire to share some food. Hunters told stories about the dangers that they faced and how they overcame them, and the children learned survival skills. The evening was also a time for planning hunting operations for the next day or for picking up the camp and moving it to a new site. A comet appearing in the night sky was a sign of impending calamity.
Not even the elders of the Clovis community had seen such a large and bright comet before. This was an ominous sign that spread fear and panic among the people. Humans were transfixed by the blazing comet overhead which was now visible even in the daytime. Some nocturnal animals may have noticed the change in the night sky, but they did not understand its meaning like the Clovis people. Unfortunately, nothing could be done to prevent the tragedy that was about to happen. All creatures living between the Rocky Mountains and the East Coast of the United States were doomed.
A comet measuring 2 kilometers in diameter traversed the Earth's atmosphere in four seconds leaving a blinding incandescent trail much brighter than the sun. The heat radiating from the comet was so intense that forests under its path burst into flames. When the comet crashed into the Laurentide Ice Sheet, the impact launched glacier ice boulders that created an expanding ejecta curtain. The crater in the ice sheet continued to widen for about 30 seconds after the initial impact, and during this time shards of ice were propelled by an expanding vapor plume. The animals and Clovis people who were close to the impact point all died from the initial shock of the extraterrestrial impact. People who were further away along the Atlantic Coast saw a flash in the horizon and two or three minutes later they felt the ground tremble from the shock wave of the comet impact.
After the comet impact launched ice boulders in ballistic trajectories, a major change took place in the motion of material within and beneath the crater. Instead of flowing upward and away from the crater center, the material came to a momentary halt, and began to move downward and back toward the center. This collapse was due to gravity and the elastic rebound of the underlying compressed layers of the target. The hurricane force winds that expanded from the impact point, now rushed back toward the center. When the major forces of the impact quiesced, the incandescent crater continued to melt the surrounding ice, triggering local flooding and forming billowing clouds of steam.
The ice pieces that were ejected by the comet impact on the Laurentide Ice Sheet had suborbital space flight trajectories that took them above the atmosphere. The ice pieces varied from a few meters to several hundred meters in size. Some pieces of ice even exceeded one kilometer in size. The pieces of ice that were wet left a trail of ice crystals along their trajectory as the water evaporated in the vacuum of space where water can only exist as a solid or a gas.
The trajectories of the ejected ice boulders had flight times of 6 to 9 minutes, depending on their launch angles and launch speeds. The blinding flash of the comet impact on the horizon was followed by a sky that darkened menacingly as it filled with the giant ice boulders ejected by the impact. Three minutes after the flash, the dark sky advanced relentlessly over an area that covered the Eastern United States.
The ice boulders re-entered the atmosphere and started crashing into the ground accompanied by deafening sonic booms. The seismic vibrations of the ice boulder impacts liquefied the ground. The saturation bombardment by the huge glacier ice boulders killed the megafauna and Clovis people. The liquefied ground was like quicksand that trapped everyone. It was impossible to walk or run. In a few seconds, everyone would be dead. The steam trails of the ice boulders reentering the atmosphere at supersonic speeds darkened the sky like the worst thunderstorm imaginable, but the thunder was from the sonic booms. The impacts created muddy craters that swallowed whole villages and buried all the vegetation. The expanding ejecta curtain trapped the jet stream and brought hurricane-strength winds to the surface.
Ten minutes after the comet impact, the ice bombardment was over, but it would be about one hour before the rumble of distant sonic booms would cease. The comet itself had not killed the megafauna. The saturation bombardment by the ice boulders that were ejected when the comet struck the Laurentide sheet was what triggered the extinction event. The ice boulders hit the fauna directly and destroyed their habitat from the Rocky Mountains to the East Coast of the United States. The ice bombardment had energy equivalent to 8 megatons of TNT per square kilometer. Any survivors away from the kill zone had to adapt to the colder climate of the Younger Dryas in order to maintain their lineage. The ones that did not adapt became extinct.
A layer of dark soil called a black mat at the Murray Springs Clovis site in Arizona marks the transition between our modern world and a land previously populated by large animals like mastodons, short-face bears and giant armadillos. Hundreds of mammoth footprints in the sand are filled by black mat sediments. The footprints and a mammoth skeleton appear to have been preserved by rapid burial after the Younger Dryas event. No Clovis points or extinct megafaunal remains have been recovered from or above the black mat, indicating that the mammoths and the Clovis hunting technology disappeared simultaneously.
Evidence is emerging that a comet fragment measuring about 2 kilometers in diameter crashed into the Laurentide Ice Sheet about 12,900 years ago. There may have been more than one impact, but there are no typical craters to prove it. Some scientists suggest that the comet fragments that hit the earth may have been part of the Taurid meteor stream, which is a field of comet pieces from the disintegration of a progenitor comet that created the meteor stream and the much smaller Comet Encke about 20,000 to 30,000 years ago. The Earth crosses this meteor stream every year from late October through November, but the core of the stream passes close to Earth every 2,500 to 3,000 years. Taurid meteors enter the Earth's atmosphere at about 28 kilometers per second.
There is a substantial body of archeological work showing that the human population declined during the early Younger Dryas. One of the lines of evidence is the number of Clovis points found at 13,000 calendar years before the present, which is just before the onset of the Younger Dryas. One thousand years later there is a decrease in points that implies a decrease in the population of the outlined study area.
The Clovis people disappeared at the onset of the Younger Dryas and many years later they were followed by the Folsom people. The reduction in the number of points is evident when the distribution is compared to Clovis points in the same region.
The study of the ballistic sedimentation of ice boulders that created the Carolina Bays provides us with a glimpse at the final moments of the Clovis Culture. It is regrettable that the demise of the Clovis culture is mentioned as just a natural incident without acknowledging the fear, anguish, and pain suffered by these people during the Younger Dryas cataclysm. Even though this happened long ago, we should feel sorrow and compassion for the people who perished during this tragic catastrophe because the same thing could happen to us.
Fitting the bays with ellipses by the least squares method is an objective way of determining their geometry. The mathematically elliptical geometry of the Carolina Bays is a clue that the bays originated from secondary impacts. The Carolina Bays did not originate from thermokarst and they were not created by wind and water mechanisms. Based on their geometry, their overlaps and their radial alignment to a convergence point by the Great Lakes, they are impact structures.
