NATURAL SCIENCES OF PHILADELPHIA. 21 



have been deposited just before the close of a period of transition from the con- 

 ditions of the Carboniferous, to those of the Permian epoch. 



The apparent absence of fossils in the beds above No. 10, renders it impossi- 

 ble, with our present information, to determine with certainty the upper limits 

 of the series containing Permian forms. It is true, there is at places a 

 kind of conglomerated mass, occupying the horizon No. 9, which might appear 

 to form a natural line of division between the beds containing the Permian 

 fossils, and those above, in which we found no organic remains ; but this 

 seems to be local, and although there is a new feature presented by the zone 

 of gypsum deposits above it, we find between the beds and layers of gypsum, 

 and far above the horizon at which they occur, bluish, greenish, and other 

 colored clays, not only similar to those between the beds and layers of limestone 

 containing the Permian fossils in division No. 10, but also precisely like the 

 laminated clays between the beds of limestone of the upper Carboniferous 

 series far below. Again, in these clays of the gypsum zone, as well as through 

 a considerable thickness of clays above it, there are occasional seams of clay- 

 stone, which sometimes pass into seams of magnesian limestone, exactly like 

 some of those containing Permian fossils, in division No. 10. We saw no 

 fossils in these seams amongst the gypsum bearing beds, nor higher in the 

 series, but it is probable they may yet be found in some of the more calcareous 

 portions. 



Another fact apparently indicating some kind of relation between the gypsum- 

 bearing beds, as well as some of the higher deposits, and the rocks below, 

 is, that we often find both in the clays between the beds of gypsum, and those 

 between the limestone containing the Permian fossils, the same peculiar appear- 

 ance caused by the cracking of the clays and subsequent infiltration of calcare- 

 ous matter, seen in division No. 5. At some places the thin plates of limestone 

 formed by the impure calcareous matter filling these cracks, may be seen rami- 

 fying through some rather thin beds of these clays in all directions, so as to 

 cross and intersect each other at every angle. Where beds of this kind have 

 been exposed for any length of time along near the tops of bluffs, the softer 

 clays filling the interstices, often weather out, so as to have a curious cellular 

 mass, with the numerous angular cavities. 



From these fact3 we are inclined to suspect, though we are fully aware that 

 it is a question which can only be determined upon evidence derived from or- 

 ganic remains, that not only the gypsum-bearing deposits, but a large portion, 

 if not all, of division No. 5, belongs to the same epoch as the beds containing 

 the Permian fossils below. 



Between No. 5, and the Cretaceous above, there is still a rather extensive 

 series of beds in which we found no organic remains ; these may be Jurassic 

 or Triassic, or both, though as we have elsewhere suggested, we rather incline 

 to the opinion that they may prove to belong to the former. As we have fully 

 discussed the question in regard to the Cretaceous age of the highest division 

 of the foregoing section in a paper read before the Academy in December last, 

 and in an article in the American Journal of Science, January, 1859, it is un- 

 necessary for us to add any thing further on that subject here. 



As already stated, our observations along the Kansas valley, to within twelve 

 or fourteen miles of the mouth of the Big Blue river, were too isolated to a deter- 

 mine in all cases the relations between outcrops seen at different places. Con- 

 sequently, although we saw at several points along this part of the valley, in- 

 dications of a westward or north-westward inclination of the strata, we were 

 left in some doubt whether or not there is a general inclination of the rocks in 

 that direction, between Wabounse and the Missouri. Above this point, how- 

 ever, our observations being more connected, and the exposuies more continu- 

 ous, we were able to determine very satisfactorily that there is at least from 

 near Wabounse, a uniform dip towards the west or north-west, so that in as- 

 cending the Kansas valley from this region, we are constantly meeting with 

 more and more modern rocks, as those we leave behind pass beneath the level 

 of Kansas. 



1859.] 



