Amazon.com description: Product Description: "[...]that spores of lichens, blown towards them by the wind, were beginning to sprout upon the more settled rocks, and to discolour the surface in places with grey and yellow patches. Bit by bit, as rain fell upon the new-born hills, it brought down from their weathered summits sand and mud, which the torrents ground small and deposited in little hollows in the valleys; and at last something like earth was found at certain spots, on which seeds, if there had been any, might doubtless have rooted and flourished exceedingly.[...]".