IOWA ACADEMY OF SCIENCES. 41 



lo Ihe streams, one must readily infer that this condition exists at least to a 

 greater degree than heretofore accorded. It is a notable fact that between 

 the Guthrie and Cass county outliers there are no exposures of bedded rock 

 either of the Coal Measures or of the Cretaceous and it may even be that 

 one or more of these outliers in the one county are connected with those in 

 the other. 



Further, as results of recent investigations, new or previously unrecorded. 

 Cretaceous outcrops have been found; the southernmost deposits of this age 

 are no longer contined to central Montgomery and northeastern Mills 

 counties. 



In Montgomery county along the western slope of the ridge lying adjacent 

 to and east of the East Nishnabotna, Cretaceous beds were recognized by an 

 almost continuous exposure from Red Oak, the locality where White 

 claimed the southernmost Cretaceous existed, to the south boundary of the 

 county. The character of the bed varies here from a tine white to brown 

 nou-tirm sandrock to a compact pudding stone. This latter is composed 

 largely of pebbles from one-fourth to one-half an inch iu diameter, imbed- 

 ded in a somewhat to quite siliceous limonite matrix. In some of these 

 exposures are absorbed excellent samples of cross bedding. At Coburg, 

 only one mile north of the south line of Montgomery county a bluff rises 

 abruptly from the outer margin of the here rather broad alluvial plain. 

 Near the base of this bluff is a bed of fine friable sandrock eighteen feet 

 thick lying beneath a few feet of coarser sand, small pebbles occurring in 

 bands, over which bed I'ests about ten feet from the pudding stone. This 

 entire section presents an elegant cross bedded character. About half way 

 between this point and Red Oak these same beds occur and are more fully 

 exposed. The total exposed thickness of the lower sandstone is thirty feet 

 while that of the overlying pudding gtone is perhaps as great. This latter rock 

 is very hard and firmer than any Cretaceous rock yet noticed in Iowa, 

 and is quite persistent in this vicinity, withstanding to a great degree the 

 eroding agencies, so preserving the under deposits. 



Two and a half miles eastwai'd from Cobarg, on the county line a soft, 

 Cretaceous sandrock rises above Ramp creek forming on the south side of the 

 creek a perpendicular bluff twenty feet iu height. South of this bluff, in 

 Page county, small outcrops of such stone are noticed; some in the slope of 

 the hill higher than the top of the bluff' just mentioned. On the hill to the 

 northward a well entei-ed the sandstone at an elevation some higher than 

 that of the top of the creek bluff. These facts go to prove that the thick- 

 ness of the bed here is not much less than it is found to be in northern 

 Montgomery county. The bottom of the bluff extends into the bed of the 

 creek and only a short distance up the stream Coal Measure limestone 

 crops out, with no perceptible dip in any direction, several feet above the 

 water, indicating again the unconformability of the Cretaceous upon the 

 lower rocks. 



In Page county about one mile east of Essex (Tp. 70 N., R. XXXIX W.) 

 the pudding stone such as described elsewhere, is found exposed along 

 the roadside. Here it has about the same relative position above the East 

 Nishnabotna as at points farther northward. This outcrop is only twenty 

 miles north of the Missouri line and is decidedly the southernmost exposure 

 of the formation recorded as existing in Iowa. South of this exposure 



