56 ON THE GEOLOGY AND NATURAL HISTORY 
ing 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 divi- 
sion 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 
claystone, 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 appearance, caused by the cracking of the clays and 
subsequent infiltration of calcareous 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 ramifying 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 ex- 
posed for any length of time along near the tops of bluffs, the softer clays filling the inter- 
stices often weather out, so as to have a curious cellular mass, with the numerous angular 
cavities. 
From these facts we are inclined to suspect,—though we are fully aware that it is a 
question which can only be determined upon evidence derived from organic 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 Cretace- 
ous 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 unnecessary for us to add anything further on that subject here. 
As already stated, our observations along the Kansas valley, to within twelve or four- 
