BROADHEAD — COAL MEASURES IN MISSOURI. 325 



most part unfit for useful purposes. The limestone meas- 

 ures 433 feet or 21 per cent, of the whole, while there is 

 only about one per cent, of coal. 



DESCRIPTION OP GROUPS. 



Group A. — This Group includes the highest rocks found 

 in the State, and occurs in Atchison and adjoining counties. 

 Its base appears at Forest City, and passing northeast- 

 wardly is found at N.E. part of Holt County, dips beneath 

 the Nodaway Eiver at Quitman, is found eastwardly on 

 Sand and Florida Creeks in Nodaway County ; thence 

 diverges northeastwardly. 



In Atchison County the upper members are found along 

 the river bluffs, and also on Eock Creek. 



This Group is distinguished for its great thickness of 

 shales and sandstone, and small proportion of limestone. 

 The latter are generally very pyritiferous and inferior for 

 building or for lime, and readily decompose from exposure. 



The blue limestone occurring near the base is Avell mark- 

 ed and easily recognised by the occurrence of a small Lin- 

 gula which I have found only in this rock; it is also the 

 lowest range of Productus Calhounianus, Sw., and PJuom- 

 phalus complanatus? A Gervillia has been found in 

 No. 41, and Fusulina cylindrical? abounds in the lime- 

 stones throughout the Group. A trace of bituminous coal 

 occurs in No. 10. At Yancton and above White Cloud 

 there crops out a seam of coal varying from 8" to 10" in 

 thickness, and of good quality. At Forest City, in No. 43, 

 a seam occurs varying from 2" to 4" in thickness ; this 

 thickens northwardly; it occurs in Nodaway County on 

 several branches of Nodaway Eiver, and is worked at several 

 places. On Nodaway Eiver, near the State line, it is divid- 

 ed by shales. On Florida Creek Chonetes and Spirigera 

 occur in the coal. 



Some of the sandstones are useful for building purposes. 

 Near the State line on Nodaway Eiver, argillaceous shale 

 is used for making brick. 



Group B. — This might properly be placed in the next 

 lower Group, but as that is more well marked, and its upper 

 and lower members are more intimately connected, I have 

 separated it, and placed it iu a separate group. 



It has a thickness of 09 feet and contains some beds of 

 good limestone. From a sandstone quarry at Forest City 

 excellent grindstones are made. Pr. Mogersii (Nor. & 

 Prat.), Archck ocidaris, and Chcetetes* abound. The latter of 



* This Chrrtftes also occurs on Grindstone Creek ; DeKalb County, and on Brush Creek, 

 Caldwell County, in Group " E." 



