117 ERA OF THE CRETACEOUS FORMATION. The record of this period consists of a series of strata, in which chalk beds make a conspicuous appearance, and which is therefore called the cre taceous system or formation. In England, a long stripe, extending from Yorkshire to Kent, presents the cretaceous beds upon the surface, generally lying conformably upon the oolite, and in many instances rising into bold escarpments towards the west. The celebrated cliffs of Dover are of this formation. It extends into northern France, and thence north-westward into Germany, whence it is traced into Scandinavia and Russia. The same system exists in North America, and probably in other parts of the earth not yet geologically inves tigated. Being a marine deposit, it establishes that seas existed at the time of its formation on
