st.johx.1 MESOZOIC AEEAS JURASSIC. 495 



covered and brought in from the region south of this a beautiful 

 collection, including several species of this genus ; but at the present 

 locality tins Ceratites limestone and associated beds are in so confused 

 a state as to render their relations either to the well-determined Jurassic 

 on the one hand, and the equally characteristically marked Upper Car- 

 boniferous on the other, a subject of much perplexity. However, the 

 Ceratites bed unquestionably overlies the Upper Carboniferous, between 

 the siliceous beds of which and this particular horizon intervenes a space 

 of between a quarter and half a mile across, in which obscurely exposed 

 red-earth or arenaceous deposits occur. Hence, it would appear that 

 the Ceratites bed probably occurs at the base of the Jurassic, though it 

 may possibly pertain to the upper portion of the Trias, to which the red 

 arenaceous deposits probably belong. A few miles due west of this 

 locality, where the same or inferior limestones of the Jura are pretty 

 well exposed, in the often-mentioned ridge west of the Blackfoot, the 

 occurrence of Ceratites, if they exist in these .beds, was overlooked ; but 

 in the outlying belt on the east flank of the Carboniferous ridge south 

 of John Gray's Lake, just over our southern border, fragments of similar 

 gray limestone were observed, but not in situ, which abounded in these 

 interesting fossils. At the latter locality apparently a heavy series of 

 red arenaceous deposits, comparable with the Triassic "red beds," tills 

 the space intervening between the Carboniferous ridge and the low ridge 

 in the crest of which the Ceratites limestone debris was found. The two 

 above localities were the only places where this rock was observed within 

 our district, and I have mentioned all the facts elicited in relation to its 

 occurrence in order, if possible, to contribute something towards the 

 data for establishing the stratigraphic position of the horizon. 



The remnants of Jurassic strata elsewhere occurring in the Blackfoot 

 Bange afford little of interest in this special connection. 



To the northeast in the mountainous belt of the Caribou Bange the 

 Jurassic deposits enter largely into the stratigraphic structure of a sys- 

 tem of folds, which are finely displayed in some of the deeper canons 

 crossing the range transverse to the direction of the folds, which deter- 

 mined that also of the mountain range. On the northeast flank of the 

 northern part of the range these deposits reach a thickness of 2,000 to 

 3,000 feet, but neither above nor below could the exact limits of the 

 series be satisfactorily determined. It consists of limestones, drab and 

 variegated shales, and indurated calcareous shales, with occasional hori- 

 zons of brownish and reddish sandstones. A fair understanding of the 

 deposits in this quarter may be gathered from the section through Sta- 

 tion XXIV. The Jurassic limestones and shales at this locality are 

 overlaid by a heavy ledge or ledges of quartzitic sandstone, beyond 

 which, in successive superimposed positions, occur heavy beds of red 

 arenaceous materials and drab indurated calcareous deposits, which ap- 

 pear to be conformable with the older formations. 



To the southeastward much the same series of deposits were encoun- 

 tered as far as our examinations were carried. But in the section here 

 presented we in vain seek for the counterpart of certain horizons which 

 perform so important part and are so well characterized, paleontologically 

 and lithologically, in the southwestern areas of this formation. The dis- 

 tribution of the fossils would appear to be much more general, with fewer 

 local faunae, such as were found in the arenaceous limestones on Lincoln 

 Creek. The forms most prevalent are a small Ostrea(?) and one or two 

 forms of small Gasteropods, the specific affinities of the latter, owing to the 

 indifferent state of preservation of the specimens, being indeterminable, 

 although they may belong to Viviparus. However, there occur other 



