314 ON THE DEPOSITS CALLED TERTIARY most, and under a want of relation or parallelism to those strata. Thus they are easy to discover and assign; and it is no credit to geologists that they were so long overlooked, and so perpetually confounded with the secondary, and even with the primary strata, as had been done in the case of the “ bituminous marl slate.” I shall commence by making those distinctions among them which have not yet been made; and thence, as I hope, elucidate the whole subject. I must first reject entirely those strata, be they hard or loose, and whatever remains they may con tain, marine, or terrestrial, which occur in any place or country, where it can be shown by geographical investigation, that they have formed a portion of the bottom of the actual ocean. The remark, thus stated, seems so simple, that every one will accede to this exclusion: and yet that distinction has been so little made, that many of the tertiary strata described, are of this nature: as these discreditable errors have produced a very great part of the confusion which has encumbered this subject. And let it be remem bered, that if the bottom of the present ocean extends to the foot of the mountains of Upper India, as to those of British America, covered by terrestrial allu via, there are thousands of similar inland places in the world, where the same facts must exist; as it is most certain that these deposits have been often confounded with the proper tertiary strata. And these are the cases also, where the alternations of marine and ter restrial remains especially occur; under circumstances precisely the same as are now taking place on many sea shores, and especially at the aestuaries of rivers. To class these with other tertiary strata, is to place an effectual bar to all knowledge or hope of order: they must be ranked with alluvial formations; for to