184 Twenhofel — Granite Bowlders. 



Shale ...: 10' 815' 



Limestone 10 825 



Limestone and shale 10 835 



Limestone 10 845 



Blue shale 20 865 



Limestone and shale 25 890 



Shale 5 895 



Limestone 5 900 



Sandstone and shale 10 910 



Dark shale 145 1055 



Light shale with gas 15 1070 



Dark shale 30 1100 



Sandstone 25 1125 



Shale 150 1275 



Limestone 6 1281 



Three other wells have been drilled about a quarter of 

 a mile southeast of the place where the bowlders are most 

 abundant and one about a half a mile southeast. Three 

 of the wells are about an eighth of a mile from the most 

 eastern occurrence of the bowlders. The writer has not 

 seen the logs of these wells, but if granite were present 

 in any one of them it has not been made known. 



The information from these wells weakens the hypo- 

 thesis that the granite bowlders may have been derived 

 from a dike which lies directly beneath. The evidence, 

 however, is not conclusive, since none of them is suffi- 

 ciently close to have penetrated a dike if it were in any 

 degree vertical in position. 



Powers has suggested that the bowlders have perhaps 

 been derived from a local granite elevation which "might 

 have been undergoing erosion somewhere in the vicinity 

 of Woodson County during the deposition of the LeRoy 

 (Weston) shales." 4 "When the bowlders were first dis- 

 covered, the country was quite thoroughly gone over by 

 the writer and others who made the search in his interest 

 and this work has been more or less continued to the 

 present time. At no other place in this vicinity has a 

 single trace of granite been discovered. Wells have 

 been drilled all around the region — the logs of many of 

 these have been examined by the writer — and in none of 

 them is granite known to have been discovered. Such a 

 granite elevation, however, may be present, but, if so, 

 erosion has probably not yet uncovered its summit. 



4 Powers, Sidney; this Journal, 49, 146-150, 1917. 



