THE SWEETLAND CREEK BEDS 1 



In Muscatine, Bloomington, Sweetland, and Montpelier 

 townships, of Muscatine county, Iowa, some argillaceous beds 

 are frequently found overlying the Cedar Valley limestone 

 These contain a fauna quite different from that of the latter, and 

 are unconformable with this as well as with the Coal Measures 

 above. For reasons which will presently appear it is proposed 

 to call them the Sweetland Creek beds. 



Typical exposures. — Following the north bluffs of the Missis- 

 sippi westward, the first occurrence of these beds is to be seen 

 in the bank of a creek which comes down from the north, just 

 east of the town of Montpelier. About twenty rods north of the 

 bluffs the basal sandstone of the Coal Measures rests on some 

 olive-gray shale, with green bands, rising about three feet from 

 the bed of the stream in the right bank. This shale is alto- 

 gether unlike the dark shale of the Coal Measures in appear- 

 ance. The layers are more even and uniform. An unconformity 

 between the two is also evident, and the lower formation soon 

 disappears. In the river bluff the same creek is undermining a 

 cliff of Coal Measure rock, which rests on the Cedar Vallev 

 limestone for the greater part of its length, but at the south end 

 the base of the Coal Measures rises somewhat abruptly, first on 

 an eroded slope of the limestone, and then over some decayed 

 yellow clayev beds which intervene and run up ten or twelve feet 

 above the limestone. The present condition of the bank does 

 not afford an opportunity to closely study the nature of the clay 

 beds, but in all probability they belong to the same strata as the 

 shale above. 



To the west of the town, a short distance up in Robinson 

 Creek, and just northwest of Mr. G. W. Robinson's residence, 

 some green clay is seen in the south bank of the creek, appar- 



1 Published by permission of the State Geologist of Iowa. 



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