3 Quotes Tagged: ice-sheets

As the discoverer and principal excavator of Murray Springs, [...] Haynes deserves credit for drawing attention to a very curious aspect of the site — a distinct dark layer of soil draped 'like a shrink-wrap,' as Allen West puts it, over the top of the Clovis remains and of the extinct megafauna — including Eloise.
Haynes has identified this 'black mat' (his term) not only at Murray Springs but at dozens of other sites across North America, and was the first to acknowledge its clear and obvious association with the Late Pleistocene Extinction Event. he speaks of the 'remarkable circumstances' surrounding the event, the abrupt die-off on a continental scale of all large mammals 'immediately before deposition of the ... black mat,' and the total absence thereafter of 'mammoth, mastodon, horse, camel, dire wold, American lion, tapir and other [megafauna], as well as Clovis people.'
Haynes notes also that 'The basal black mat contact marks a major climate change from the warm dry climate of the terminal Allerod to the glacially cold Younger Dryas.'
From roughly 18,000 years ago, and for several thousand years thereafter, global temperatures had been slowly but steadily rising and the ice sheets melting. Our ancestors would have had reason to hope that earth's long winter was at last coming to an end and that a new era of congenial climate beckoned. This process of warming became particularly pronounced after about 14,500 years ago. Then suddenly, around 12,800 years ago, the direction of climate change reversed and the world turned dramatically, instantly cold — as cold as it had been at the peak of the Ice Age many thousands of years earlier. This deep freeze — the mysterious epoch now known as the Younger Dryas — lasted for approximately 1,200 years until 11,600 years ago, at which point the climate flipped again, global temperatures shot up rapidly, the remnant ice sheets melted and collapsed into the oceans, and the world became as warm as it is today.

Areas that are densely populated today, Chicago, New York, Manchester, Amsterdam, Hamburg, Berlin, Moscow — in fact most of North America and northern Europe — were absolutely uninhabitable due to the fact that they were covered by ice-caps several kilometers thick. Conversely, many areas that are uninhabitable today — on account of being on the bottom of the sea, or in the middle of hostile deserts such as the Sahara (which bloomed for about 4000 years at the end of the last Ice Age) — were once (and relatively recently) desirable places to live that were capable of supporting dense populations.
Geologists calculate that nearly 5 per cent of the earth's surface — an area of around 25 million square kilometers or 10 million square miles — has been swallowed by rising sea-levels since the end of the Ice Age. That is roughly the equivalent to the combined areas of the United States and the whole of South America. It is an area almost three times as large as Canada and much larger than China and Europe combined.
What adds greatly to the significance of these lost lands of the last Ice Age is not only their enormous area but also — because they were coastal and in predominantly warm latitudes — that they would have been among the very best lands available to humanity anywhere in the world at that time. Moreover, although they represent 5 per cent of the earth's surface today, it is worth reminding ourselves that humanity during the Ice Age was denied useful access to much of northern Europe and North America because of the ice-sheets. So the 25 million square kilometers that were lost to the rising seas add up to a great deal more than 5 per cent of the earth's useful and habitable landspace at that time.

We know that relatively minor sea-level rises could set off major ice-sheet breakups, and it has been suggested by Stephen Oppenheimer that the tremendous earthquakes caused by isostatic rebalancing at the end of the Ice Age could have stirred up 'mountain-topping superwaves' in the northern regions of the Atlantic and Pacific Oceans. Other than Oppenheimer's own investigations, however, my impression is that while many brilliant individual scientists have studied individual post-glacial phenomena in great depth, very little has yet been done to investigate all these phenomena together as part of a complex system or to consider the effects on the earth and its human population of multiple, interacting cataclysms — floods, lands subsiding into the sea, earthquakes, volcanic eruptions — all occurring at the same time.