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IOWA ACADEMY OF SCIENCE 
Other sections measured nearby in the same bluff showed con- 
siderable variation from that given above, owing to differential 
erosion of the St. Louis prior to the deposition of the Pella and 
to the variable character of the basal beds of the Pella itself. 
The section presented, however, may be regarded as typical. 
In another bluff on the opposite side of Peed creek, about 300 
yards above the location of the preceding section, the Pella beds 
are seen to rest upon somewhat lower beds of the Upper St. 
Louis. At this point, bed No. 10 of the foregoing section is 
represented by 18 feet of limestone; bed No. 9 by 3y2 feet of 
shale; and beds 5, 6, 7 and 8 collectively by a continuous bed 
of sandstone varying from 24 to 34 feet in thickness. The un- 
derlying St. Louis is badly mashed for the most part, and to- 
wards the top the matrix of the brecciated limestone is abund- 
antly filled with sand grains derived from the overlying forma- 
tion. The basal sandstone of the Pella attains a similar devel- 
opment in the vicinity of Keosauqua, whence the name Keo- 
sauqua sandstone as applied by Gordon.® It there in many 
places includes discontinuous, lenticular masses of compact, 
sparsely fossiliferous limestone. 
Fauna . — As regards the fauna of the Pella beds, at least two 
distinct faunal zones are distinguishable. These are repre- 
sented in the thin shale bed which usually follows the unfossilif- 
erous basal sandstone and in the overlying limestone member 
which normally caps the formation in southeastern Iowa. The 
shale member is characterized predominantly by a pelecypod 
fauna, but the brachiopod, Pugnoides ottumwa, and a small 
ostrocod, Leperditia sp., are also common. In the Indian creek 
section (Section II, bed 10), this bed yields the following forms: 
Pugnoides Ottumwa (White) 
Sphenotus (several undescribed 
species) 
NucuTa illinoisensis Worthen? 
Leda curta M and W.? 
Myalina sp. undet. 
ScMzodus (several undescribed 
species) 
Aviculopecten sp. 
Modiola sp. 
Allorisma (species undescribed) 
Solenospira sp. 
Leperditia sp. undet. 
A collection from the same bed on Eeed creek (Section IV, 
bed 9) yielded the following species: 
Pugnoides ottumwa (White) species) 
Bolenomya? iowensis Worthen? Glossites (species undescribed) 
SpJienotus (several undescribed Edmondia (species undescribed) 
»Ia. Gteol. Survey. Vol, IV, 1894, p. 217. 
