398 ILLINOIS STATE ACADEMY OF SCIENCE 



NOTES ON THE WATERLOO ANTICLINE 

 J. Everts Lamar^ State Gteological Survey, Urbana 



The Waterloo anticline is located between the towns of 

 Columbia and Waterloo, in Monroe County, Illinois, 

 abont 28 miles southeast of St. Louis. The structure was 

 first worked out by Dr. Stuart Weller in connection with 

 his geologic mapping of Monroe County for the Illinois 

 State Geological Survey. In the fall of 1920 a heavy oil 

 was encountered in the Kimmswick limestone in a well 

 drilled for water by the Waterloo Condensed Milk Com- 

 pany. Shortly afterwards two press bulletins were is- 

 sued by the State Geological Survey, the first by Mr. H. 

 E. Culver, and the second by Mr. L. A. Mylius, in which 

 the structure was delineated and recommendations made 

 for drilling. This is the most recent case where the Sur- 

 vey has called attention to favorable field conditions and 

 directed successful exploration. 



Up to the present time there have been 55 wells drilled 

 on the anticline, and of this number 33 are producers, 12 

 dry with a showing, 3 incomiDlete, and 7 dry. Wells with 

 good locations on structure come in at from 75 to 125 

 barrels, but soon drop off to 25 or 50 barrels per day. 

 They do, however, make good consistent pumpers, and 

 because of the nature of the pay are likely to be long lived. 



the structure of the WATERLOO ANTICLINE 



The structure is that of a long, narrow, sharp crested 

 asymmetrical anticline, extending aj)proximately from 

 north to south, with its maximum width of about one 

 mile near the north end, and tapering abruptly to the 

 north, but extending as a long, narrow fold for about 31^ 

 miles to the south. The total length of the anticline is 

 about five miles. 



The west flank is by far the steeper side with an aver- 

 age dip, as indicated by structure contours on the 

 Kimmswick limestone, of about 10° to the west. In the 

 vicinity of the producing area it is cut by a normal fault 

 with its upthrow side to the east, which probably dies out 

 into a monocline to the south. This fault brings inclined 



