stable sea level

31 Jul 2015

A small piece in the news section of Current World Archaeology 72 (Aug, 2015) (see www.world-archaeology.com) caught my eye - as these things do. Some 13,000 year old footprints of a man, woman and a child were found on the shoreline of an island off the coast of British Columbia - dating back 13,000 year ago (which is very nearly the Younger Dryas boundary), alongside a hearth and two cobble tools. They were made by people walking over grey clay which was then infilled by black sand and that preserved the footprints (we are told). The really interesting point then made is that this shows that specific places on the Pacific coast of Canada were used over a long period - and 'sea level has been very stable in the region over the last 14,000 years'.

The stable nature of sea level in this part of Canada appears to contradict mainstream thinking - and the various graphs made of rising sea level from the Ice Age to the present. This is not something that should be ignored. It raises an important question - was sea level rise at the end of the Ice Age, or at the point of any other climatic anomaly in the Holocene, really global in nature (or was this an assumption made by researchers who could see sea level changes in the Atlantic basin). Sea level rise is in itself an important component of Ice Age theory. This is that ice sheets covered large areas at the top of the world. When temperatures warmed these ice sheets melted and caused global sea levels to rise. However, according to the archaeologists in the research above - no such sea level rise occurred in at least one region of the world. We may wonder then if there was an ice sheet covering western N America as the evidence is not as compelling as that for the north eastern side of N America.

Several possibilities arise. We may think in terms of an ice sheet covering a limited area of the northern hemisphere (for whatever reason) and therefore its melting did not cause much of an affair on a global scale. Or we may think in terms of a very rapid rise in sea level after the end of the Ice Age (between 16,000 and 14,000 years ago) which would contradict the models created of slow and gradual sea level rise which grace most of the textbooks on the Ice Age. However, another problem is also apparent as they are also saying there was not much of a sea level rise in northern British Columbia around 8000 years ago (6000BC) which can be seen in other parts of the world. This may imply the latter is greatly exaggerated (for whatever reason) or that sea level rise around 6000BC had nothing to do with rising global sea levels but was more to do with changes in the earth's geoid - including a redistribution of the water at the equatorial bulge. Presumably this would not have affected British Columbia as it was far from the tropics - but why did it affect the British Isles? (assuming the drowning of the southern North Sea basin and large tracts of the Channel were related to the same phenomenon).

Various other problems arise. The drowning of Beringia, a land mass lying between Alaska and NE Siberia, is assumed to have occurred at the end of the Ice Age. It must have been a very rapid rise in sea if it is not visible after 14,000 years ago, and must have all been over by the Younger Dryas. Therefore sea level may have risen along the coast of British Columbia - but before 13,000 years ago. How does this affect the archaeology of the migration route between Siberia and the Americas?