288 INDEX TO THE STRATIGRAPHY OF NORTH AMERICA. 



The change of names from the Tazewell to the Estillville quadrangle indicates 

 the uncertainty attending the selection of formational and also of systemic bound- 

 aries in the two sections. The relations of the Kimberling shale to the Grainger 

 shale and of the Romney shale to the Chattanooga shale have not been traced across 

 an unsurveyed gap of a few miles. The Grainger may include part of the basal 

 Mississippian. 



The Grainger shale has been mapped by Keith through the Morristown and 

 Maynardville quadrangles, Tennessee, to the vicinity of Knoxville (longitude 84° 

 west, latitude 36° north), and it is accompanied by the Chattanooga shale, which 

 extends beyond to Georgia and Alabama. 



Along the base of the Cumberland escarpment across Tennessee, from the Brice- 

 ville through the Kingston and Chattanooga quadrangles, into Georgia, the Devonian 

 is represented only by the Chattanooga shale, which ranges in thickness from 80 feet 

 in the northeast to as little as 10 feet in the south. In its occurrences in Georgia 

 and Alabama the Chattanooga shale is remarkable for the persistency with which 

 it retains its character, although everywhere very thin. 



In the Coosa Valley of Georgia and Alabama the Frog Mountain sandstone (of 

 Oriskany age) lies unconformably upon Ordovician rocks. Hayes ^'* described the 

 occurrence as follows: 



There are between Indian and Weisner mountains several small areas occupied by a forma- 

 tion which comes in contact with all the older formations thus far described. It consists of 

 coarse ferruginous sandstone, in some places white, resembling quartzite, and in others yellow 

 or gray and weathering to incoherent beds of sand. Beneath this sandstone and usually deeply 

 covered by its debris are shales, also variable in composition and appearance. No satisfactory 

 measurement has been made of their thickness, but this is probably as variable as their physical 

 appearance. 



Schuchert"" determined the following Oriskany forms from this sandstone: 



Orthis (Rhipidomella) musculosa Hall. 

 Stropheodonta niagiiifica Hall. 

 Anoplotheca fimbriata Hall. 

 Spirifer tribulis Hall. 

 Meristella cf . walcotti Hall and Clarke. 

 Amboccelia umbonata Conrad. 



K 10. KLAMATH MOUNTAINS, NORTHERN CALIFORNIA. 



Among the Paleozoic strata of the northern Sierra the Devonian is recognized 

 by an Onondaga fauna. The fossils are corals, which in places form reefs, and the 

 terrane itself consists of limestone, 50 to 70 feet or more thick, which is associated 

 with schists and eruptive rocks. ^' 



Diller has brought together the available information regarding the Devonian 

 of northern California. He distinguishes the southwestern and northeastern belts, 

 which may be recognized on the map'. Concerning the former he says : ^^^^ " In the 

 southwestern belt there is a line of Devonian limestone lentils (formerly doubtfully 

 referred to Jura-Trias) which may be traced with many interruptions for over 100 

 miles parallel with the. South Fork of Trinity River." In the detailed descriptions 



