The Earth's Shifting Crust by Charles Hapgood - wire of information

THEICEAGES 47
revelation that the last North American ice sheet had indeed
disappeared at a very recent date. Tests made in 1951 showed
that it was still advancing in Wisconsin as recently as 11,000
years ago (272:105); later tests indicated that the maximum
of the ice advance may have been a thousand years later than
that. When these dates are compared with other dates showing
the establishment of a climate like the present one in
North America, it seems that most of the retreat and disap-
pearance of the great continental icecap (with its 4,000,000
square miles of ice) can have taken little more than two or
three thousand years.
What is the significance of this new discovery, besides
showing how wrong the geologists had been before? The fact
is that so sudden a disappearance of a continental icecap
raises fundamental questions. It endangers some basic as-
sumptions of geological
science. What has become of those
gradually acting forces that were supposed to govern glaciation
as well as all other geological processes? What factor can
account for this astonishing rate of change? It seems self-
evident that no astronomical change and no subcrustal
change deep in the earth can occur at that rate.
When this discovery was made, I expected that the next
revelation must be to the effect that the Wisconsin ice sheet
had had its origin at a much more recent time than was sus-
pected, and that the whole length of the glacial period was
but a fraction of the former estimates. I had a while to wait,
because radiocarbon dating in 1951 was not able to answer
the question. By 1954, however, the technique had been im-
proved so that it could determine dates as far back as 30,000
years ago. Many datings of the earlier phases of the Wisconsin
glaciation were made, and Horberg, who assembled them,
reached the conclusion that the icecap, instead of being 150,ooo
years old, had appeared in Ohio only 25,000 years ago
(222:278-86). This conclusion has been so great a shock to
contemporary geology that some writers have sought to evade
the clear implications, by questioning the radiocarbon meth-