But while, in this particular case, the size of the comet, or its more fiery nature, melted the surface of the globe, and changed the very texture of the solid rocks, we find in the geological record the evidences of repeated visitations when Drift was thrown upon the earth in great quantities; but the heat, as in the last Drift Age, was not great enough to consume all things.
In the Cambrian formation, conglomerates are found, combinations of stones and hardened clay, very much like the true "till."
In the Lower Silurian of the south of Scotland, large blocks and bowlders (from one foot to five feet in diameter)
[1. Dana's "Text-Book," p. 156.]
{p. 434}
are found, "of gneiss, syenite, granite, etc., none of which belong to the rocks of that neighborhood."
Geikie says:
"Possibly these bowlders may have come from some ancient Atlantis, transported by ice."[1]
The conglomerates belonging to the Old Red Sandstone formation in the north of England and in Scotland, we are told, "closely resemble a consolidated bowlder drift."[2]
Near Victoria, in Australia, a conglomerate was found nearly one hundred feet in thickness.