A Brief history of the Pleistocene is that around 15 to 20 thousand years ago glacial ice pack reached it’s maximum depth covering much of the northern continents of earth with as much as two miles of solid ice and snow pack. It was not the first ice age in the last million years but one of many. It was the ice age that set in place many environmental conditions that remain with us today, From 15 thousand years ago to 10 thousand years ago There were a series of continental glacial melt downs , re freezing and regrowth of those glaciers. The largest sustained melt down of the continental glaciers occurred between 11 thousand years ago and 10 thousand years ago. Some where between 15000 years ago and 12000 the mega fauna extinction occurred . Animals that included giant tree sloths, saber tooth tigers and Mammoths all disappeared in this extinction. Somewhere within this time line the Clovis people with their distinctive stone age flint arrow and spear tips appear in the fossil / archaeological record giving scholars an incentive to connect the mass die off of larger mega fauna species with human hunting activity. New theories have emerged to say a massive asteroid or comet might have hit the vast continental ice cover of ice age North America and this could have been the reason for the mega fauna die off. Had it been a larger comet hitting that could also explain what would later be seen as the cause of a sudden increase in carbon dioxide in the atmosphere with a big Maybe attached to it leading to the earth’s continued warming in phases from 15000 years ago to the present. The increase in carbon dioxide detected in every warming period is more likely an effect and not a cause from global warming because more of the earth’s continental surface maybe exposed to plant growth and subsequent fires when uncovered by glaciers.
There is a totally different way to look at the transformation of the topography of the earth before , during and after the ice age melt down and this alone offers up many different scenarios for the great mass mega fauna extinction that occurred in the Pleistocene that can certainly compete with the best of the existing theories. Instead of trying to find exact time period dates I think one should just look at the topological changes involved in the great melt down of the up to 2 mile thick ice glaciers that covered most of what is now Canada and much of Northern USA , Northern Siberia and elsewhere.
Reality was that as the continental glaciers incrementally grew and grew in area and dept they deprived the oceans of water that got locked away in continental ice. The sea levels around the world fell significantly . We know that sea levels dropped to a maximum of 400-500 feet below the present day levels when the continental ice was at a maximum. When sea levels were this low Britain was connected by land to the rest of Europe and even to Denmark and Sweden. Florida was twice as big in land area as it is today. The continental shelves around the world were dry land. Europe’s Mediterranean sea was a lot smaller than it is today. The Black sea was high and dry land. Land areas were extended all over the world and these lands were often covered with lush vegetation especially in the tropics. Whole continent like islands that were high and dry are now submerged around the world. This incredible change in sea level is all too often ignored as a viable part of the theory on why carbon levels in the atmosphere may have changed and why the mega fauna went extinct. It is also noted as a factor in who and what the Clovis people were. They may have only been the more primitive of humans around in those Prue-historic times. Underwater archaeological study is beginning to show that civilization probably predates Ancient Egypt’s rise around 7000 years ago. We know in our own world that the most viable human settlements tend to be located on the coast lines. Those coastlines are now 400 feet under water thanks to the ice melt down. Around the world from the Adriatic sea to the California coast we are finding evidence of human settlement far below sea level that dates to the Pleistocene. It is all around the world. The best of archaeological evidence is yet to be discovered and chances are it will be making the high tech Clovis people seem like inland remote primitives of the time. The great ice age cities would have been located perhaps within the black sea basin before it flooded or on the coast lines of India and maybe along the eastern Mediterranean sea? Ice age cities is pure speculation but the facts are that humans had a whole different world to occupy during the time that the continental ice reserves were stable and not melting. We know that continental glaciers were moving because we see the geological remains on earth’s surface where they moved and carved mountains or scored the earth. The whole ice age was dynamic and sea levels did rise and fall faster then we are used to in our historic record period. Humans are considered to have been more nomadic as hunter gatherers mostly in those times so that settlements could have been built over 100 feet above ice age sea levels and have been safe for thousands of years of climate change.
The idea that nomadic people were only hunter gatherers is perhaps wrong. We know today that the American Plains Indians “managed” the bison herds. They intentionally burned the land to improve conditions for their prey. Once you know that was happening it is very hard to believe that humans would have behaved so destructively as to destroy their source of sustenance. The bison / buffalo remained a non-domesticated animal but it was still being managed in spite of remaining wild. Somewhere between domestication and management is how Reindeer herds are owned and managed by people today in places like Finland. The reindeer are still mostly wild but they are herded. Humans were most likely the best of friends to mega fauna species they considered to be useful and would not have been hunted to extinction. Humans would have likely adopted baby mammoths the same way they take wild elephant babies and attempt to “domesticate” them today. Discounting the human technological ability to cause mass extinctions does not mean that would be something that would be necessary. A Mammoth kill could last a very long time for an average size tribe. Humans would have studied how mammoths would only have one offspring at a time and would probably have made a point of hunting only excess males that were outcasts of the herds and left the females alone. Humans lived for more almost a million years with Mega fauna without mass extinction event until the one and only final event. There is a good chance that because much of the land mass where human settlements were are probably underwater now that what we know about human advancements in agriculture and civilization occurred much earlier than we previously thought. The evidence we have for the origins of agriculture only come from above present sea level archaeological sites.
The real cause of the Mega fauna probably has to do more with what happens when 400 ft of sea level ice suddenly melts on continents at at once or just 5 or ten percent at a time. OK say just 10 percent of the continental ice melted in just one summer what would that be like? Well every river and every lake would be subject to catastrophic flooding on the continents where the ice sheets existed. As this melting occurred sea levels would just as instantly rise 40 feet.. OK maybe it was not that sudden. Maybe it took 100 years for this kind of melting to occur mostly over 100 separate summers. That would also mean catastrophic flooding in low lands and it would far more than double the flow of rivers on an annual basis especially with other precipitation likely The great ice age melt down came fast and was furious. When melting glaciers move faster than than they do when at a lower temperature. What happens as enough water to raise sea levels 400 ft melts over 1000 years or less? Flooding, Faster moving glaciers scoring the underlining land, catastrophic flooding events such as what happened to the black sea and to the Columbia River Gorge when a giant flood almost instantly carved out a deep gorge 1000s of miles long in the landscape after an ice dam broke. The aftermath is lush vegetation areas are downed under water all over the world. The oxygen producing terrestrial plants no long do this under water. If the ice comes back they emerge from the water and are subject to fire as dead biomass. Once the melting begins again they are permanently submerged under sea water. Whole environments disappear under water. Whole islands and some as big as small continents disappear for good. Meanwhile continental land mass that used to be under the glaciers is being exposed. This land has had most of its top soil plowed away by the movement of the glaciers or redeposited in other places than from where it may have originally been laid down as bio mass laden sediments. As the glaciers melt catastrophically season after season what ever remaining soil that exists is subject to being washed away depending on elevations. In some cases the melt down flooding will just fill existing lakes with soil sediments. The reason the Grand Canyon’s Colorado river appears to run in the wrong direction may just be because of the catastrophic melt down waters? Two mile high glaciers melting just leave you with a lot of problems with flooding on an on going basis and lots of climate change issues especially for the areas on earth that were formerly above sea level.
Today we talk about climate change and never think about how climate changes when sea level actually rise over our heads completely destroying parts of our natural ecosystem’s ecology in a permanent way. Terrestrial land also was going from reflective ice covered glaciers with nothing growing on top of them to bare land that used to be below them with essentially nothing able to grow there immediately because most of the soil was taken away by the ice melt and the scoring to bare rocks below the glaciers as they moved. Imagine a 1 mile high 5000 ft glacier cliff advancing a few feet a day in places during the height of the melt down and think about the environment being this perfectly balanced ecosystem we are always being told that only humans can upset. That kind of thing really did happen in the ice age melt down during a window of just about 5000 years. The biggest melt downs we know happened even faster. Where I live in Portland geologists told me that during the ice age period silt from low lands blew up on top of the rocky hills leaving a 50 foot deep clay sediment on the mountain sides. It is still here today. Much of this silt that became clay did not blow up on top of the hills of Portland in just one year. It took hundreds and thousands of years for so much to end up where it did. What that means is that as glaciers receded glass lands and forests were not able to grow up to prevent the wind from blowing silt and sand long distances and even up hill, The low lands must have been unable to sustain life during a long period of time for 50 ft of this very fine clay silt to have been blown up as much as 2000 ft in elevation. It would not have been easy to breath this fine sediment either. It might be that some ferns and conifers would have pioneered the wet rock cut landscape left by the receding glaciers . At the same time much of the best low lying grass and forest lands would be being submerged as sea levels were rising. Where do you get the grass seed to blow into to start growing in the wastelands left as the glaciers melt and how long can they stay planted when the next catastrophic flood could happen as any moment or just part of the front of the glacier could collapse falling more than a thousand feet ahead of its southward advance.
This gives us a totally different picture of why the mega fauna would have just all gone extinct over the period of several thousands of years with no need at all for humans to take any of the blame. There is accelerated glacial advancement, catastrophic flooding, lack of soil, huge areas of the continents being submerged below sea level with an entire intact ecology going there with it and a huge continental wasteland being left in places where the glaciers used to be. If we map the earth and do an assessment of the damage to the environment , if you want to call it that, due to the melt down then we see something extraordinary that we should have expected to see but did not because of our temptation to think that the earth’s environment / ecology naturally stays in some state of balance when it does not. The Hole melt down process just on the North American Continent over a period of several thousand years destroys everything that used to be a picture perfect ecology under 400 ft or more of ocean water. Where the glaciers used to be exposes more than 2/3rds of the continent that was formerly under ice initially exposing a huge wasteland where very little is initially able to grow. Add it together and look at the loss of habitat and it is between 80 and 90 percent of the north America is in a state of ecological catastrophic shock. This is not true in tropics there the wasteland under the glaciers is not exposed but there huge amounts of the best land for forests and savanna to thrive are under water. The big question of why the mega fauna extinction occurred is not as hard to answer once you see the catastrophic trans-formative change that was occurring. It did not all occur at once but we do know that the it did occur in a long series of catastrophic events in a very short geological time span. 1000 to 5000 years seems like a long time to us but it is a very fast period of time in the geological record where we find out that the Hawaiian Islands may only be 25 million years old in their formation. Imagine that sea levels were to rise about half a foot per year in our life times. New York city would already be under water. The sea levels would rise 0.40 ft per year if the melt down of the glaciers lasted 1000 years for sea level to have risen 400 feet. Nature was not at all kind to flora and fauna or even humans around the world to have had this great meltdown going on. The idea of mega fauna catastrophic die offs is something only humans could have done under the circumstances is absurd. Australia also lost its mega fauna at about the same time and it had no great glacial ice cover. Australia was however subject to the fast sea level change with rapidly rising levels of water. Parts of the great barrier reef around Australia would have been high and dry land back then. Transformation around the world was fast and furious. It is possible that an asteroid or comet might have been the cause of the ending of the ice age but that is a different story. The meltdown of two mile high ice sheets has enough cat atrophic consequences built into it to do all the harm possible by itself. At some point once a pre-ice age or ice age era city of sophistication equal to that of present day archaeological sites is discovered then at that point we will know that humans may have only been lucky to have survived the melt down themselves. So often the environmentalists are telling us how horrible it is that humans have “disturbed” the natural landscape with “over development” when the reality is that we humans are completely at the mercy of nature. The warming of the planet since the ice age may be what made it possible for humans to become such a large part of the biological diversity on the planet. Talking about the planet’s ecosystems somehow being disturbed by humans is absurd considering the amount of disturbance there was just because the last ice age came to an end. Another most interesting fact seems to be that the carbon levels in the atmosphere appear to increase in warming phases of the earth without any human industrial use of fossil fuels being required. Anyone telling us that humans have disturbed the planet know nothing about their geological history as a means of making an insightful comparison of just how much things can be disturbed by nature alone.
Don’t Ever Tell Me Humans and Our “Over Development” thanks to our 7 Billion People Population is “disturbing” the Natural Balance of the Earth or It’s Climate! Don’t Even Bother to Try Making an Argument like This Until You Put Human Causes and Effects into a Comparison with the “disturbances “caused by all by itself.” The end of the ice age in all of its phases over a 5000 year period of time was one catastrophe after another where humans themselves were at risk of surviving.