CORRELATION OF CARBONIFEROUS ROCKS 349 



only Permian forms were observed. Although we regarded 

 these upper beds as the true representatives of the Permian, we 

 gave a section of the whole series, down so as to include a con- 

 siderable thickness of beds below, with lists of fossils, showing 

 the range of the various types, without drawing any line of 

 demarkation, because we were satisfied nature had nowhere 

 defined any abrupt physical or paleontological break here in the 

 series," 1 .... that is, that there is in this region [Kansas], a 

 gradual shading off from an upper Coal Measure to a Permian 

 fauna, through a considerable thickness of strata, formino- a 

 somewhat intermediate group, which we called the Permo-Car- 

 boniferous series ; also that there is no defined break between 

 this intermediate series and the Permian above, or the Coal 

 Measures below." 2 



It is also true that Hayden did not abandon the correlation 

 of the highest Paleozoic rocks of Kansas with the Permian, for 

 in July, 1867, he published some "Notes on the Geology of 

 Kansas," in which he reviewed "Swallow's Preliminary Report 

 of the Geological Survey of Kansas," not accepting his division 

 of the Lower Permian as of true Permian age, and said: "As 

 we ascend in the series, we find that, after going some distance 

 above the supposed line of demarcation [Swallow's between 

 the Lower Permian and Coal Measures] the Carboniferous 

 species gradually begin to disappear, and the Permian types 

 become rather -more common, in particular beds, until we have 

 ascended to a point near the horizon Professor Swallow makes 

 the line between the Upper and Lower Permian, when we find 

 we have almost completely lost sight of the familiar Carbonifer- 

 ous species, a few of which had continued on up to near this 

 point, and see scarcely any but forms such as in Europe would 

 be regarded as Permian types. There is no physical break 

 here, however, nor abrupt change of fossils. Hence Meek and 

 Hayden regarded the beds below the horizon down so far as to 

 include most, if not nearly all, of Professor Swallow's Lower 

 1 Am. Jour. Sci. 2d ser. Vol. XLIV, 1867, p. 334. 

 "Ibid, pp. 338-339. 



