DEVONIAN. 283 



together, although it can not be definitely stated that the former fossil does not appear as low 

 down in the limestone as the highest occurrences of the characteristic coral. 



Conformably overlying the Nevada limestone occurs a heavy body of black shale, which 

 has been designated as above, it having been first recognized as a distinct horizon in the WMte 

 Pine mining district to the southeast of Eureka. It occupies a clearly defined stratigraphic 

 position with a marked change of sedimentation and a fauna distinct from both the underlying 

 and overlying horizons. 



Impressions of plants, which are exceedingly rare in Paleozoic rocks of the Great Basin, 

 are very abundant and form a distinctive feature of this epoch, notwithstanding that every- 

 thing which has been collected has been of a fragmentary nature. The most promising speci- 

 mens for identification were submitted to Sir William Dawson, who, in his report, called atten- 

 tion to the poor state of preservation of the plants. Under date of Montreal, June 11, 1889, 

 he writes: 



"One slab contains a small ribbed stem referable to Goeppert's Anarthrocanna, a doubtful 

 Calamitean plant. The specimen is not unlike those found at Perrj'', in Maine, and Bay de 

 Chaleur. On the large slab is also a slender branch stem which I suppose may be the stipe of 

 a fern, and from its character and angle of ramification probably belongs to the genus Aneimites, 

 but no trace of the pinnse can be seen. The evidence, so far as it goes, would indicate the 

 Upper Devonian (or Erian, as I prefer to call it), rather than the Middle Devonian or the Lower 

 Carboniferous." 



It will be seen that this determination as to the age of the plants is quite in accord with 

 the geological position of the beds above the Nevada limestone of the Devonian and directly 

 below the Diamond Peak quartzite of the Carboniferous. 



Girty^^^" in 1905 tentatively placed the White Pine shale in the Carboniferous 

 and correlated it with the Caney shale of Arkansas. He says : 



In the "White Pine district of Nevada the beds called "Lower Carboniferous" by Mr. Wal- 

 cott, which are suggested to be of Pottsville age, are underlain by a black shale — the White 

 Pine shale — which he assigned to the "Upper Devonian." I have long been of opinion, however, 

 that the age of this bed is not Devonian, but Carboniferous. The White Pine fauna, however, 

 is not without forms suggestive of the Devonian, to which period it was also tentatively assigned 

 by Meek. One of the most striking of these is a Leiorhynchus resembling L. quadricostatum. 

 Productus Mrsutiformis and a Posidonomya (Posidoniella ?) also lend it a Devonian aspect. A 

 Leiorhynchus like L. quadricostatum, a Productus like P. Mrsutiformis, similar Goniatites, and 

 similar Posidoniellas, are found near the base of the Caney shale in Indian Territory, and in 

 the Spring Creek limestone and FayettevUle shale of Arkansas. These facts, together with a 

 similarity in lithologic character and an identity in stratigraphic position, in point of which 

 each occurrence is immediately beneath beds supposed to represent about the same horizon, 

 while not sufficient to demonstrate stratigraphic equivalence, for which a thorough comparison 

 of the entire faunas would be necessary, lend a strong color of probabihty to it. 



Eastward from Nevada the Devonian thins notably. It was supposed to be 

 represented in the Wasatch . section by the Ogden quartzite of King,^"^* but the 

 formation has since been determined to be the Middle Cambrian quartzite repeated 

 by an overthrust. Blackwelder^^® says : 



Kindle" has recently shown that the Jefferson limestone of Montana, with a sxifficient 

 Devonian fauna, extends southward into the mountains of Utah, and he has traced it along 

 the east side of Cache Valley, in the Bear Eiver Eange. He has also identified in the same 

 locality a limestone containing Silurian fossils conformable beneath the Jefferson formation. 



" Kindle, E. M., Bull. Am. Paleontology No. 20, Ithaca, N. Y., 1908. 



