24:6 W. Gross — New Devonian Formation in Colorado. 



invertebrates of Colorado. The Ouray limestone has been 

 studied in several quadrangles of the San Juan region, the 

 original locality at which its Devonian fauna was first dis- 

 covered by Endlicli has been revisited, and its position as a 

 well determined unit in the Paleozoic section of Colorado must 

 be considered as established. The present paper refers to 

 the immediately underlying formation, in which Endlich foand 

 fish remains, and which is now for the first time given a dis- 

 tinctive name. 



The locality at which Endlich first observed the Devonian 

 strata lies upon the southern slope of the Needle Mountains, 

 about 10 miles east of the Animas canyon at Eockwood, and 

 on the western rim of the Yallecito canyon. The beds are very 

 near the base of the Paleozoic section which dips southerly 

 under the influence of the post-Laramie doinal uplift about the 

 Needle Mountains center. Erosion has removed the sediments 

 over a large area, in places exposing the coarse-grained granite 

 upon which they rest and here and there leaving tongues or 

 isolated patches of the lower formations. 



The Devonian invertebrates were found by Endlich at a tri- 

 angulation station, obscurely referred to in his report as " Sta- 

 tion 48," which is easily identifiable from the topographic 

 report of 1874 as the point of elevation 12,305 feet, according 

 to the Hayden map, directly overlooking the Vallecito canyon 

 and a little south of the boundary of the Needle Mountains 

 quadrangle. A stone monument still stands at the point, upon 

 a remnant of Ouray limestone very rich in fossils and near 

 the base of the formation. A branch of the Yallecito, 

 heading west of the point, cuts it off from the main sloping 

 mesa of sedimentary rocks, which begins a half mile to the 

 southwest. In the absence of sufficient geographic terms for 

 descriptive purposes, the writer proposes the name "Devon 

 Point" for this knoll capped by Ouray limestone, the "Station 

 48 " of the Hayden survey, which must become a classic spot 

 in the discussion of the Colorado Devonian. The name End- 

 lich Mesa has already been given, upon the Needle Mountains 

 topographic map, to the gently dipping surface of granite and 

 thin overlying Paleozoic beds which lie between the Yallecito 

 and the Florida rivers, and is terminated by the headwaters of 

 the latter stream. Devon Point lies on the eastern edge of 

 Endlich Mesa. 



Below the triangulation monument of Devon Point there are 



but about 25 feet of the Ouray limestone. Intervening between 



the limestone and the granite are two distinct formations referred 



to by Endlich* in the following terms, which (as to the upper 



*Loc. cit. pp. 211, 212. 



