Throughout an enormously large proportion of the ocean, the bright blue tint of the water bespeaks its purity.

The many cases on record of a formation conformably covered, after an immense interval of time, by another and later formation, without the underlying bed having suffered in the interval any wear and tear, seem explicable only on the view of the bottom of the sea not rarely lying for ages in an unaltered condition.

The remains which do become embedded, if in sand or gravel, will, when the beds are upraised, generally be dissolved by the percolation of rain water charged with carbonic acid.

Some of the many kinds of animals which live on the beach between high and low water mark seem to be rarely preserved.