131 



Midway Stage 17 



a. Soil. 



b. Enclimatoceras limestone: yellowish and gray, more 

 or less friable; exterior of fossils often stained brown 

 by iron oxide; replete with Enclimatoceras idrichi, 

 varying in size from i to 12 inches in diameter, 18 inches. 



c. Ostrea limestone: compact, light gray limestone, con- 

 taining innumerable specimens of Ostrea pulaskensis, 3 feet. 



d. Turritella limestone: light yellowish and gray, some- 

 what sandy; often honey-combed and cavernous, 

 weathering very irregularly; at base especially, re- 

 plete with Turritella mortoni, - - S}{ feet 



e. Sandstone ledge, light yellowish; formed apparently 

 by infiltration of waters charged with calcite, into 



sand like that below, - - - - 2^ feet. 



/. White, compact sand, tinged yellowish on the exte- 

 rior; contains scattering blue nodules. Exposed, 2 feet. 

 g-. " Black slate, lying nearly horizontal; seen only at 



times of very low water." — Olsen. 

 The molluscan species are Enclimatoceras idrichi, Ostrea crenuli- 

 marginata, O. pidaskensis, Cucidlcea saffordi, Yoldia eborea, Cras- 

 satella, Venericardia planicosta, Protocardia, Cytherea {Dosiniop- 

 sisf), Corbula subcompressa, Tornatellcea cf. bella, Calyptrophorus 

 velatics, Vohdilithes probably saffordi, Pyrula, Mesalia alabamie?i- 

 sisf, Titrritella mortoni, T. alabamiensis , T. midtilira, Scala sp., 

 Natica alabamiensis . 



Farther to the southwest about y^ mile a compact gray lime- 

 stone appears in the bed of a stream just north of the railway 

 track. This has furnished specimens of Cucidlcza saffordi, Cy- 

 therea {DosiJiiopsis) , Crassatella, Venericardia planicosta (large), 

 Calyptrophorus velatus. 



In lyittle Rock, from Capitol Hill to the County Hospital, 

 Midway limestone is frequently met with. The best collections 

 made by the Arkansas Survey were frpm Johnson's well on 

 Capitol Hill. Some were imbedded in light clayey, crystalline 

 limestone, while others were from more yellowish and sandy 

 layers. The forms identified are Ostrea cre7udimarginata, Cu- 

 cidlcea saffordi, Meretrix sp., Venericardia planicosta, Protocardia, 

 TornatellcBa, Vohdilithes probably saffordi, Mesalia alabamiensis, 

 and large typical Turritella mortoni. 



Featherstonhaugh records from this limestone at Little Rock, 

 Ostrea, Turritella, Calyptrea, Cerithium, etc. 



Lonoke county.— \u the vicinity of Cabot this limestone has 

 been seen and it has furnished a few Midway species. 



White county.— Again, perhaps i^ miles north of Bradford, a 



