PAPERS ON GEOLOGY AND GEOGRAPHY 199 



with the Tully limestone of the New York section. The 

 Wapsipinicon and Cedar Valley limestones are both pre- 

 sent in Rock Island County, Illinois, and the following mem- 

 bers of the Wapsipinicon limestone are recognized in that 

 region : Otis beds ; Lower Davenport limestone ; and Up- 

 per Davenport limestone. 



WAPSIPINICON LIMESTONE 



The Otis Beds outcrop on Campbell's Island in the Mis- 

 sissippi River above Moline, and a few low exposures oc- 

 cur in the Illinois bank of the River in that vicinity. This 

 is gray to dark non-magnesian limestone, commonly rather 

 fine grained, and somewhat irregularly bedded. The thick- 

 ness does not exceed 15 or 20 feet. It is succeeded in this 

 region by the Lower Davenport limestone without any 

 trace of the Kenwood Shale. The Lower Davenport mem- 

 ber consists of strongly brecciated nonfossiliferous lime- 

 stone, the fragments of which are gray to dark, fine 

 grained, and show fine laminations on weathered surfaces. 

 The matrix is also fine grained, but is somewhat lighter in 

 color. This brecciated limestone is exposed in the Govern- 

 ment Island at Rock Island, and is the horizon formerly 

 quarried in Rock Island and Moline. The Lower Daven- 

 port limestone is overlain in apparent conformity by the 

 Upper Davenport member which is composed of gray, 

 granular, subcrystalline limestone, in irregular layers 

 from a few to twelve inches or more in thickness, and con- 

 tains several fossils, among which Phillipsastrea billingsi, 

 Diplophyllum major, Schizophoria macfarlanei, Gypidula 

 comis, and several Cephalopod species are characteristic. 

 This member is well exposed in the vicinity of Sears and 

 Milan. 



CEDAR VALLEY LIMESTONE 



The Cedar Valley limestones are commonly more shaly, 

 more evenly beaded, and more richly fossiliferous than those 

 of the Wapsipinicon which they succeed without any sedi- 

 mentary break. They outcrop in the banks of Mill Creek, 

 and farther west along several of the creeks both east and 

 west of Andalusia. These limestones are commonly rather 

 thin bedded, shaly and obliquely jointed in the lower part. 



