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

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EARTH'S SHIFTING CRUST
he would have trouble in finding a reasonable basis for the
latter conclusion.
We can therefore conclude that, on the whole, the North
American icecap is a good candidate for the position of prime
mover in the last displacement of the crust. The argument
will be strengthened when we consider, below, its detailed
history, and the implications of the extraordinary tempo of
its development and of its subsequent decay. The essential
argument in favor of icecaps is the time factor, for the rate
of their accumulation and of their melting is obviously many
times faster than that of any other process creating unbalance
in the distribution of materials on the earth's surface.
Horberg has recently collected and studied, as already
mentioned, the radiocarbon dates bearing on the history of
the Wisconsin ice sheet. According to him, the following is
its short and violent history (222:281):
a. The first known advance of the icecap its first appearance
in Ohio is dated at merely 25,100 years ago. This
is called the "Farmdale Advance." It was formerly thought
to have occurred as much as 100,000 or even 150,000 years
ago. This date, then, cuts the time for the later history of
the ice sheet by about three quarters. Six different radiocarbon
dates, all of the Farmdale Advance, show that the ex-
pansion continued until at least 22,900 years ago, or for
about 3,000 years. Then there was an unexplained interval
of warm climate (which I will explain later on), called the
"Farmdale-Iowan Interstadial." This warm period lasted
about 1,500 years, during which the ice withdrew a certain
distance.
b. Following the recession, a new advance of the icecap
occurred. This is referred to as the "lowan Advance." It
began about 21,400 years ago, lasted about 700 years, and
was interrupted by a new recession about 20,700 years ago.
c. This second recession, after less than a thousand years,
was succeeded by an extremely massive advance during the
period from 19,980 to 18,050 years ago.
These dates must
not be taken as absolutely exact; there is always a small mar-