138 J. W. Beede — Correlation of tlie Guadalupian 



may be a very different matter. The base of tlie Capitaii 

 falls near the bottom of the Elnidale formation stratigraphi- 

 cally, wiiich is, probably, not far from its correct fannal corre- 

 lation as well. The paleontological comparisons are 3'et to be 

 worked out. The nnconforniity above the Capitan limestone 

 and locally even on the Delaware Mountain formation, the 

 Capitan having been carried away, is not taken into account in 

 making these comparisons.* It is probable that it diminishes 

 rapidly to the northward, where it is of less consequence. 



One of the most interesting features of the Guadalupian 

 fauna is its isolation. As has been stated by Girty, the fauna 

 is a unique one, and, as a unit, is now known from no other 

 part of the western hemisphere. At first thought it seems 

 peculiar that more of its members were not distributed ov,er 

 the adjacent regions where contemporaneous strata occur. 

 Theii- absence in such rocks has been a serious difliculty in any 

 attempt to correlate them with other American faunas. 



In tlie first place, the lower red beds lying to the eastward, 

 with which the Guadalupian limestones are probably contem- 

 poraneous, are believed by some to be to a considerable extent 

 of subaerial origin, while the temporary seas that occupied 

 portions of it from time to time were too concentrated in salt 

 content for normal marine faunas. So far as my collecting in 

 the typical Capitan limestone goes, the fossils were abundant 

 only in the purer limestones, and were very rare or wanting in 

 what appeared to be the dolomitic portions of it. These lime- 

 stones occur in the Apache Mountains and at Guadalupe Point, 

 but appear to be wanting, as does the fauna, north of the 

 Texas line; the only exceptions noted were Fusulina elongata^ 

 and one or two other species in Dog canyon and Sitting Bull 

 canyon. From this it will be seen that the fauna was closed 

 off on the north by untoward conditions and on the east by the 

 red bed sedimentation, which constituted a barrier. iSlo other 

 barrier is known. 



Two other considerations must be taken into account. First, 

 that the Permian facies of this fauna may be an abnormally 

 early precursor of the Permian faunas developed in an isolated 

 basin. f Such an occurreiice of Permian forms is known in 

 Kansas well down in deposits of Pennsylvanian age. However, 

 the variety and richness of the Guadalupian fauna, which pos- 

 sesses such a young appearance, seem to me to argue against 

 this hypothesis. Second, the other possibility is that the fauna 

 is no older than it appears and that it developed normally 



* Richardson, Univ. Min. Surv. Tex., Bull. 9, pp. 43-44, 1904. 



f The idea of local isolation of the fauna was first suggested to me by 

 David White and later, at the meeting of the Paleontological Society, by J. 

 M. Clarke. 



