Geology and Mvneralogy. 237 



strips of silvered glass, through the middle of which a scratch of 

 about 0*002 ram breadth was made in the silver surface. This 

 scratch served as a spark gap. An investigation was made upon 

 the absorption of electrical waves by different substances. Ebo- 

 nite, parafine and rock salt showed no absorption. Green glass, 

 quartz-selenite and olive oil showed clearly absorption. — Pendie, 

 M. Ace. dei Lincei, (5) 2, 1 Series, pp. 505-518, 1893. j. t. 



II. Geology and Mlnekalogy. 



1. On the Devonian ( Oriskany) in the Southern Appalachians; 

 by C. Willaed Hates, U. S. Geological Survey. (Communi- 

 cated.) — In a letter written in January, 1891, concerning the 

 Devonian rocks of the Southern Appalachians I made the follow- 

 ing statements: "In the highly faulted region between Weisner 

 and Indian mountains, in Alabama, are some coarse ferruginous 

 sandstones which appear to rest directly on the Rockmart slate 

 (presumably of Trenton or Hudson age), without any intervening 

 rocks corresponding to the Rockwood formation further north. 

 Fossils have been collected in this ferruginous sandstone concern- 

 ing which Mr. Walcott in a letter to Mr. Russell says : ' The 

 fossils collected by Mr. Cooper Curtice in a sandstone on the side 

 of Frog Mountain, Ala., include Zaphrentis sp. ?, Chaetetes com- 

 planataf, Spirifera arenosa? , 8. arrectaf, Pterinea? sp. ?, Platy- 

 ceras sp. ? All of the specific determinations are uncertain, as 

 the material is not in a satisfactory condition, but the horizon of 

 the Oriskany sandstone is strongly suggested by the general 

 facies of the fauna.' The following species which Mr. Russell 

 collected at Frog Mountain were also determined by Mr. Wal- 

 cott, ' Horizon of the Oriskany sandstone of the New York sec- 

 tion ; Zaphrentis sp. ?, Orthis muscidosaf, Spirifer arenosa, Con- 

 rad, Pentamerus cast like that of P. oblongus, Conocardium.'' 



" A few miles south of Cedartown, Ga., the stratigraphic rela- 

 tions are shown better than in the disturbed region about Frog- 

 Mountain though no fossils have been collected. Resting on the 

 Rockmart slate is a bed of sandstone not more than twenty feet 

 thick, and upon this is a fossiliferous chert which I assumed to be 

 the Fort Payne (Carboniferous). There may be an unconformity 

 above the sandstone or below it or both." 



During the past season this region was re-examined and some 

 further conclusions reached, which may be of interest to you. No 

 fossils in addition to those mentioned above were collected, so 

 that the question of the age of these rocks, in so far as it depends 

 on palseontologic evidence, remains essentially as in 1891. Their 

 relations to underlying formations, however, are better under- 

 stood. The sandstones in question at present rest unconformably 

 upon all older formations of the region, from the Middle Cam- 

 brian up to the top of the Lower Silurian. In studying a region 

 so extensively faulted as that between Weisner and Indian Moun- 

 tains, the natural tendency is to attribute all unconformities to 



