Says one authority:

"The origin of the unstratified drift is a question which has been
much controverted."[1]

Louis Figuier says,[2] after considering one of the proposed theories:

"No such hypothesis is sufficient to explain either the cataclysms or
the glacial phenomena; and we need not hesitate to confess our
ignorance of this strange, this mysterious episode in the history of
our globe. . . . Nevertheless, we repeat, no explanation presents
itself which can be considered conclusive; and in science we should
never be afraid to say, _I do not know_."

Geikie says:

"Many geologists can not yet be persuaded that till has ever formed
and accumulated under ice." [3]

A recent scientific writer, after summing up all the facts and all
the arguments, makes this confession:

[1. "American Cyclopædia," vol. vi, p. 112.

2. "The World before the Deluge," pp. 435, 463.

3. "The Great Ice Age," p. 370.]

{p. 9}