20 THE JOURNAL OF GEOLOGY. 



of the exposed gravels, was carried along the bluff just inside of 

 its margin, opening out into the river at the point where the 

 bluff turns toward the north-east. It was a trenching more com- 

 plete and more satisfactory than any of which I had ever 

 dreamed. At no point for the entire length of the bluff did the 

 excavation depart more than forty feet from the line of the ter- 

 race face — from the upper margin of the slope upon which such 

 plentiful evidence of a supposed gravel man had been obtained. 

 The accompanying map and section, Figs, i and 2, will indicate 





O * " 





^^^^^^^^^^^^^ 



Fig. 2. Sections made by the river and by the sewer, the former yielding many 

 " implements," the latter yielding none. 



the location of the trench, and show the exact relations of the 

 natural and artificial exposures of the gravels. 



I made several visits to the place, descended frequently into 

 the great cut and examined the gravels and their contents with 

 the utmost care, but without securing a trace of art. Recogniz- 

 ing the vital importance of utilizing to the fullest extent this 

 opportunity of testing the art -bearing nature of the gravels at 

 this point, I resolved to undertake a systematic study of the 

 subject. Summoning my assistant, Mr. William Dinwiddle, 

 from his field of operations in the South, I had him spend 

 upwards of a month at the great trench, faithfullv watching the 

 gravels as they were exposed. Mr. Dinwiddle had worked 

 three years under my personal direction, and had helped open 



