IOWA ACADEMY OF SCIENCES. 95 



Iowa. The Aspinwall coal seam in southeastern Nebraska and 

 northeastern Kansas is probably a part of the same stratum. 



These extensive shales impart certain peculiarities to the 

 topography of the area occupied hy the Nodaway coal that are 

 not noted elsewhere in the Missouri region. The soft rocks 

 have permitted a moderately uniform plain to be worn out. 

 In Missouri, Marbut has designated the jolain Maryville low- 

 land, thus recognizing it as one of the important relief features 

 of that state. The shales, moreover, occupy the bottom of 

 what is known as the Brownville syncline. Owing to the atti- 

 tude of the strata, their softness, and the peculiarities of the 

 drainage of this region, by which the lowland plain has been 

 formed and the contrasts of relief reduced, little information 

 has been heretofore obtained regarding the shales. They 

 have been scarcely noted, though they are two and one-half 

 times as thick as the whole upper coal measures were once 

 thought to be. Since their extent has been recognized the 

 Atchison shales have come to assume more and more impor- 

 tance, until it has come to be suspected that eventually they 

 may possibly have equal taxonomic rank with the Des Moines 

 series. 



Prosser's name Wabaunsee is admirably defined, according 

 to modern standards, and to its author represents far more 

 than a term applied in a district in which he has not worked. 

 To an unprejudiced observer, however, and to one who has 

 been over both fields, Broadhead's group cannot fail to be 

 regarded as equally well portrayed. 



Cottonwood Limestone. — The name Cottonwood limestone has 

 been adopted for the uppermost member of the Missourian 

 series. The rock was widely known as a quarry stone, long 

 before its importance as a geological formation was recog- 

 nized, it being called the "Cotton-rock, "or "Cottonwood Palls 

 rock" or "Cottonwood stone " Thus, the last two names have 

 crept into geological literature and it seems advisable to adopt 

 the title, especially since other geographic names that have 

 been applied to it have been found to be preoccupied. Cotton- 

 wood Falls and Manhattan, Kansas, may therefore be con- 

 sidered as typical localities. The formation was called many 

 years ago by Swallow the "Fusulina limestone," from its 

 most characteristic fossil feature, it being composed in 

 certain layers almost entirely of rhizopodous shells, resem- 

 bling grains of wheat. The stone is widely used for construe- 



