120 



ROCK-TRACINGS. 



a third or fourth of an inch, and at times so shallow as to be 

 barely perceptible. Those tracings, which have for hundreds, 

 perhaps for thousands, of years been laid bare to the ravages 



of the northern climate, are now most difficult to decipher, 

 while those which have been protected by earth are as fresh as 

 if they had been cut to-day ; many seem to have been cut 



