true till_."[2]

Moreover, if the sea-waves made these great deposits, they must have
picked up the material composing them either from the shores of the
sea or the beds of streams. And when we consider the vastness of the
drift-deposits, extending, as they do, over continents, with a depth
of hundreds of feet, it would puzzle us to say where were the
sea-beaches or rivers on the globe that could produce such
inconceivable quantities of gravel, sand, and clay. The production of
gravel is limited to a small marge of the ocean, not usually more
than a mile wide, where the waves and the rocks meet. If we suppose
the whole shore of the oceans around the northern half of America to
be piled up with gravel five hundred feet thick, it would go but a
little way to form the immense deposits which stretch from the Arctic
Sea to Patagonia.

The stones of the "till" are strangely marked, striated, and
scratched, with lines parallel to the longest diameter. No such
stones are found in river-beds or on sea-shores.

Geikie says:

"We look in vain for striated stones in the gravel which the surf
drives backward and forward on a beach,

[1. Dana's "Text-Book," p. 220.

2. "The Great Ice Age," p. 15.]

{p. 12}