638 HISTORICAL GEOLOGY. 



bottom is the ferruginous sandstone of Shumard. The sandstone is regarded by C. R. 

 Keyes as having been made while a final retreat of the shore line was in progress. He 

 names it the " Aux Vases" sandstone. 



The section of the Subcarboniferous at Burlington, Iowa, includes: (1) of the Kinder- 

 hook, 50'+ of clay shale ; (2) 20'- 30', soft shaly sandstone ; (3) gray impure limestone, 

 often oolitic below, 9'- 13'; (4) fine sandstone, 6'; (5) gray oolyte, 4'; (6) buff limestone, 5', 

 of the Lower Burlington ; (7) brown and gray encrinal limestone, 27'; (8) buff calcareous 

 and siliceous shales, with thin limestone layers and chert, 23', of the Upper Burlington ; 

 (9) gray encrinal limestone, somewhat cherty, 30'; (10) impure limestone with chert 

 nodules and seams, 20' (Keyes). The Keokuk exposures include about 100' of Keokuk 

 below and above Warsaw and St. Louis beds. 



Keyes has further reported (Dec, 1892) the discovery, hi northeastern Missouri, of a 

 bed of the Kinderhook limestone, containing its typical fossils, and these chiefly Mollusks, 

 intercalated in the overlying Burlington group, where typical in its f aima, and this chiefly 

 crinoidal, and without a change in lithological characters or the purity of the limestone 

 beds. It shows, as Keyes observes, that the Kinderhook and Burlington stages were not 

 wholly successive as regards time ; that after the Burlington group had made progress, the 

 Kinderhook species still existed, for a while at least, outside of their former limits, but 

 ready to return when the conditions favored. In Missouri, the whole thickness of the Sub- 

 carboniferous limestone is 1150'. 



In Indiana, the " Knobstone," below the Keokuk, has a thickness in some places of 

 500', the Keokuk of 100', the St. Louis of 330', and the Chester of 75'; the latter consists 

 of sandstones alternating with limestones. In Lawrence County, an irregular bed, or 

 series of pockets, of porcelain clay, ranging to 6' in thickness, lies at the top of the Chester 

 limestone, over a bed of iron ore. About a third is of pure white color. It has been 

 called indianaite ; with it occurs the mineral allophane. 



In Michigan, the Subcarboniferous consists of four groups of strata, according to 

 A. Winchell: (1) or lowest, 173' of grit and sandstone, called the Marshall Group; (2) 

 123' of shale and sandstone, the Xapoleon Group ; (3) 184' of shale and marlyte, with 

 some limestone and gypsum, the Michigan Salt-group; (4) the Carboniferous limestone, 

 66' thick. This limestone is well exposed at Grand Rapids. The Marshall group is made 

 the equivalent, in part, of the Kinderhook ; and the limestone , at the top, the equivalent 

 of the Chester and St. Louis gi'oups. 



In Ohio, the Subcarboniferous beds comprise the Waverly group. 



In northwestern Pennsylvania, the Subcarboniferous is in the main equivalent to the 

 Waverly. I. C. White has recognized three divisions : (1) the Oil-creek group, the equiva- 

 lent, it is believed, of the Pocono ; (2) ]\[eadville group ; and (3) Shenango group. In 

 Warren County, the Panama conglomerate is more than 200' below the top of the Che- 

 mung, and may be recognized by abundant remains of Ptychopteria. The Waverly con- 

 sists of shaly sandstones in its lower thii'd, followed by a conglomerate (= Sub-Olean ?) 

 above which are thin-bedded buff sandstones. 



In West Virginia, the Lower Subcarboniferous occurs along the middle portion of the 

 main Alleghany Mountains, from the Potomac southward. In Greenbrier County, near 

 the White Sulphur Springs, it includes a stratum of limestone 822' thick, with 1260' of 

 shales and sandstone. The limestone to the north, in Monongalia County, was found by 

 Meek, through its fossils, to be the probable equivalent of the Chester group. 



In middle Tennessee, according to Safford, the Siliceous group consists, commencing 

 below, of (1) the Protean beds, cherty and argillaceous, with some limestone, 250' to 300', 

 and (2) the Lithostrotion or Coral beds, an impure cherty limestone, the equivalent of the 

 St. Louis limestone, about 250' thick. The Upper member is limestone, 400' thick on 

 the northern borders of the state, and 720' on the southern. These two divisions occur 

 also in eastern Kentucky. The Upper member also extends into the northeast corner of 

 Mississippi, where it is overlaid by Cretaceous beds (Hilganl). At Huntsville, Ala., 



