"Sometimes it contains worn fossils, and fragments of shells, broken, crushed, and striated; sometimes it contains bands of stones arranged in lines."
In short, it appears as if it were gusts and great whirls of the same material as the "till," lifted up by the cyclones and mingled with blocks, rocks, bones, sands, fossils, earth, peat, and other matters, picked up with terrible
[1. "The Great Ice Age," p. 18.
2. "American Cyclopædia," vol. vi, p. 112.]
{p. 99}
force from the face of the earth and poured down pell-mell on top of the first deposit of true "till."
In England ninety-four per cent of these stones found in this bowlder-clay are "stranger" stones; that is to say, they do not belong to the drainage area in which they are found, but must have been carried there from great distances.
But how about the markings, the striæ, on the face of the surface-rocks below the Drift? The answer is plain. Débris, moving at the rate of a million miles an hour, would produce just such markings.
Dana says:
"The sands carried by the winds when passing over rocks sometimes wear them smooth, or cover them with scratches and furrows, as observed by W. P. Blake on granite rocks at the Pass of San Bernardino, in California. Even quartz was polished and garnets were left projecting upon pedicels of feldspar. Limestone was so much worn as to look as if the surface had been removed by solution. Similar effects have been observed by Winchell in the Grand Traverse region, Michigan. Glass in the windows of houses on Cape Cod sometimes has holes worn through it by the same means. The hint from nature has led to the use of sand, driven by a blast, with or without steam, for cutting and engraving glass, and even for cutting and carving granite and other hard rocks."[1]