Erosion of the Algonkian. How many centuries this weathering and washing
away process consumed no one knows. At the close of this epoch, however,
the Algonkian strata had been eroded almost away, owing to its tilted
condition, so that in some places even the surface of the Archaean was
exposed, and suffered the planing-down process. Figure 1 on plate facing
page 98 is a suggestion as to the possible appearance of the rocks at this
time.
Even then, in those far-away, early ages of history, if one had been
present to measure these strata, he would have discovered the astounding
fact that, although he had measured them and found twelve thousand feet
before they began to emerge from the ocean, there were but about five
hundred feet of them left. This is one of the interesting facts in
geology, - that an observant reader can deduce so much from so little.
The twelve thousand feet deposit. "But," asks the layman, "I cannot
possibly see how, if only five hundred feet of strata are left, any one
could ever tell that there were once twelve thousand feet. If eleven
thousand five hundred feet are gone, how do you know they ever existed?"
A very reasonable question and one very easily answered.
