Never, in all probability, shall we be able to point to a complete series of deposits, or a complete succession of life linking one great geological period to another.

Nevertheless, we may well feel sure that such deposits and such an unbroken succession must have existed at one time.
We are compelled to believe that nowhere in the long series of the fossiliferous rocks has there been a total break, but that there must have been a complete continuity of life, and a more or less complete continuity of sedimentation, from the Laurentian period to the present day.

One generation hands on the lamp of life to the next, and each system of rocks is the direct offspring of those which preceded it in time.

Though there has not been continuity in any given area, still the geological chain could never have been snapped at one point, and taken up again at a totally different one.

Thus we arrive at the conviction that _continuity_ is the fundamental law of geology, as it is of the other sciences, and that the lines of demarcation between the great formations are but gaps in our own knowledge..