IOWA ACADEMY OF SCIENCES. 21 



EASTERN EXTEISSION OF THE CRETACEOUS IN IOWA. 



BY CHAKLES R. KEYES. 



In connection with a casual reference to the cenological features of Central Iowa 

 mention may be made to the recent discovery in the drift at Des Moines of a mass 

 of rather soft ferruginous sandstone charged with fossils of unmistakable creta- 

 ceous type, the greater part being in a good state of preservation. When first 

 discovered the mass was perhaps two feet in diameter and contained upwards of 

 a dozen species of fossils. A iew of the best preserved specimens were taken at 

 the time; and the place revisited a few days later for the purpose of securing the 

 entire piece, but unfortunately, workmen had removed it. The species obtained 

 were: Otodiis appendiculatus Agassiz, Lamna texanci Rcemer, Fasciolaria 

 culbertsoni Meek it Hayden, Liinata concinnia. Meek «& Hayden. 



Announcements have already been made of the occurrence in the drift of Iowa 

 beyond the limits of known Mesozoic strata in situ of Cretaceous fossils and fossil- 

 iferous sandstone. Dr. White has reported an ammonite from Waterloo, Iowa, a 

 fragment of baculite from Iowa City,* and six specifically determinable forms 

 from Hardin county, f and has shown that the facies of the fossils in question has 

 a close alfinity with the fauna of the Fox Hills group, or the upper-most portion of 

 the marine Cretaceous in the continental interior. The recently discovered Des 

 Moines specimens afford additional evidence in support of this supposition. The 

 good preservation of the moUuscan remains, though so fragile, together with the 

 fact ot the comparative softness of the ferruginous sandstone, suggests, as in the 

 other cases mentioned, that the fragments of Cretaceous strata are not far removed 

 from the locality of original deposition. The satisfactory determination of the 

 easteiTi extension of the Cretaceous in Iowa is attended with much difficulty, 

 chiefly on account of the great depth of the drift, covering the northwestern part 

 of the State. But doubtless outliers will be discovered considerably to the east- 

 ward of the present ascribed limits. 



*Geol. Iowa. vol. I, p. 98. 

 +Am. Geologist, vol. I, p. 223 



