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CARBONIFEROUS LIMESTONES OF IOWA. 



SECTION OF SUBCARBONIFEROUS LIMESTONES OF IOWA. 



Bituminous shales. 



Bed of coal, six to eighteen inches thick. 

 Gray argillaceous shales. 



White, brittle, close textured limestone ; usually irregularly bedded and concre- 

 tionary. 



Brown and white gritstones, containing locally remains of Lepidodendrou, 

 calamites, and other carboniferous plants. 



B f Lower, compact, white limestone, usually concretionary; sometimes magne- 

 sian, with earthy matter and marlite in the interstices; containing two or 

 more species of Litltostrotion (slylina of Lesueur) ; including the more evenly 

 bedded limestones of St. Louis, containing melonites muttipora, several species 

 of Productus, Spirifer (bi-suladus ?), and reticulated corals of the genera 

 JRetepuru and Finesielta. 



Sandstone, sometimes with small pebbles imbedded. 



Argillaceous, cherty, and marly partings. Locally hydraulic limestone. 



'Cellular magnesian building-stone; locally with vermicular ramifications 

 and green particles disseminated. Containing reticulated corals aud 



(_ Terebrutukt Soyssii. 



Impure limestones, containing cavities lined with spars and geodes. 



{ Thin-bedded limestones with marly partings, containing Ar- 

 chimedes; also brown calcareous beds, with cells lined with 

 spars and impure limestones charged with minute Spirifer s ; 

 together with light gray limestones, containing Terebrutula 

 Royssii, Orthis ambrucuium, &c. 



Gray, crystalline limestones, containing Spirifer striatum, 

 S. cuspidatus, S. rotundatus, Productus punctatus, P. 

 semireticidutus, &c. 



• m Cherty limestones of Kiokuck. 



Brown encrinital limestones alternating with bands of 

 chert, as near Hannibal. 



^ White crystalline and semiotilitic limestones, con- 

 ( taining Productus cora and Spirifer cuspidatus. 



Brown and flesh coloured encrinital limestones, 

 containing several species of Pentremites, Pluty- 

 crinus, Actinocrinus, and Poteriocrinus. 



Brown earthy crinoidal limestones with crys- 

 talline specks. 

 Band of cellular, buff, magnesian limestone. 

 Oolitic limestone, containing Gyroceras Burling- 

 tonensis. 



\ Dark gray argillaceous limestones (locally hy- 

 ( draulic?). 



i Buff, fine-grained siliceous rock, containing casts 

 < of Chonetes, Posidonomyu, AUorisma, Spirifer, 

 ( Phillipsia. 



Ash-coloured, earthy marlites. 



( Slope, rocks hidden by talus and 

 5gs\ i alluvium of the. Mississippi River. 



