OCR Text |
Show s 402 k APPENDIX B.- GEOLOGY. The route from the Missouri westward shows a continuation of this limestone as far as the Big Blue. Here it disappears, judging from specimens and remarks in the notes. It is soon succeeded by strata of cretaceous age, which, from the specimens preserved, I have been able to recognise as extending for a considerable distance on the route between Turkey Creek and Big Sandy. Among the cretaceous fossils are a species of PholadomyOy and the Inoceramus, which is so common and abundant in numerous localities in this region. It is quite probable that these beds extend much farther, but I find no specimens in the collection; and the notes indicate that there are heavy deposites of drift, which may have obscured the exposure of the formation below. This drift formation, ( judging from the descriptions given in the notes,) or the debris from the immediate geological formation, appears to have covered the older stratified deposites, since no mention is made of # them till approaching the forks of Platte River on the 25th June. At this point were collected some specimens of clayB with small marine shells, too imperfect for determination; but from the general character, and from the occurrence of bones in the same place, it is presumed that they are of tertiary age. Above the forks of the Platte River similar bones and shells are noticed, and, on the 1st of July, specimens of bones were collected. Numerous fragments of bones were collected on the 3d of July, apparently belonging to some mammalia of the herbivorous character. These bones are too imperfect for determination beyond their general character. From the description of the mode of occurrence, and their being imbedded in a matrix of considerable hardness and tenacity, one would be led to infer that they were of some tertiary deposite. Among these specimens is a single ramus of the lower jaw, which apparently belonged to some carnivorous animal; but no teeth are preserved in it, nor were any teeth of any kind found in the collection. From July 3d to 11th, the notes give no evidence of any thing of special interest. On the latter date, bones are mentioned as occurring in the locality examined, but no specimens having this date are preserved in the collection. It would appear that the character of the country from near Fort Kearny to near Fort Laramie is uniform, and that no de- |