22 THE JOURNAL OF GEOLOGY. 



at most, exposed to the same depth by an artificial trench, was 

 so avoided by him that it does not furnish the least memento 

 of his presence. One vertical slice of the gravels twelve feet 

 thick does not yield even a broken stone, while another slice not 

 probably one-half as thick, cut obliquely through t;he gravels 

 near by, has furnished subject - matter for numerous books and 

 substantiation for a brace of theories. That no natural line 

 of demarcation between the two section lines is possible, is 

 shown by the fact that the formations are continuous, and that 

 the deposits indicate a constant shifting of lines and areas of 

 accumulation ; thus it was impossible for any race to dwell con- 



FiG. 3. a. Reputed " implement " producing zone of the river front, b, Barren 



zone of sewer. 



tinuously upon any spot, line or plane. This is well shown in the 

 section, Fig. 3, which gives the relations of the art-producing sec- 

 tion of Dr. Abbott to the non-art-producing section of the sewer. 

 The gravels were laid down entirely irrespective of subsequent 

 cutting, natural or artificial; yet we are expected to believe that 

 a so-called gravel man could have resorted for a thousand years 

 to the space a, leaving his half shaped or incipient tools at all 

 stages of the gravel building from base to top, failing entirely to 

 visit a neighboring space b, or to leave there a single flake to 

 reward the most faithful search. It is much easier to believe 

 that one man should err than that a guileless race should thus 

 conspire with a heartless nature to accomplish such extraordinary 



