Twenhofel — Granite Bowlders. 133 



for the bowlders, if they were really transported as the 

 writer has suggested. 



One of the hypotheses considered when the bowlders 

 were discovered, and one that was subsequently sug- 

 gested by others with whom the writer discussed the 

 problem, is that there may be a dike in the Pennsylva- 

 nian sediments at this place, and it was pointed out in 

 the original article that the linear distribution of the 

 bowlders is in harmony with such an interpretation. 

 The coarse texture of the granite composing the 

 bowlders and the absence of metamorphism of the adja- 

 cent sediments led, however, to the rejection of the hypo- 

 thesis. Recently a well has been drilled about a quarter 

 of a mile almost due south of the largest accumulation 

 of the bowlders, and its record, as given below, throws a 

 little light on the possibility of a dike at this place. 



Soil 2' 2' 



Clay plus lime 33 35 



Limestone 40 75 



Shale 75 150 



Limestone 20 170 



Shale 5 175 



Limestone and shale 10 185 



Shale 35 220 



Limestone 5 225 



Shale 25 250 



Limestone do 305 



Shale 40 345 



Limestone 10 355 



Limestone and shale 20 375 



Limestone 25 400 



Sandstone 10 410 



Red shale 30 440 



Red limestone 5 445 



Sandstone and red shale 10 455 



Black shale 5 460 



Limestone 5 465 



Shale 10 475 



Limestone 85 560 



Shale 80 640 



Limestone 20 660 



Red shale 15 675 



Limestone 60 735 



Red sandstone 35 770 



Sandstone and shale 20 790 



Limestone 15 805 



