SIGNS OF FORMER GLACIATIOX. 127 



means of estimating ; but the exact date and rate of destruc- 

 tion are immaterial. On this receutly-fornied ledge I saw sev- 

 eral straight furrows half au iuch broad, some of them very 

 nearly parallel, others diverging, the direction of the former 

 being north 35° east, or corresponding to that of the shore at 

 this point. After walking about a quarter of a mile, I found 

 another set of similar furrows, having the same general direc- 

 tion within rive degrees ; and I made up my mind that, if these 

 grooves could not be referred to the modern instrumentality of 

 ice. it would throw no small doubt on the glacial hypothesis. 

 When I asked my guide — a peasant of the neighborhood — 

 whether he had ever seen much ice on the spot where we stood, 

 the heat was so excessive (for we were in the latitude of the 

 south of France, 45° north), that I seemed to be putting a 

 strange question. He replied that, in the preceding winter of 

 1841, he had seen the ice, in spite of the tide, which ran at the 

 rate of ten miles an hour, extending in one uninterrupted mass 

 from the shore where we stood to the opposite coast at Parrs- 

 borough, and that the icy blocks, heaped on each other, and 

 frozen together or "packed" at the foot of Cape Blomidon, 

 were often fifteen feet thick, and were pushed along, when the 

 tide rose, over the sandstone ledges. He also stated that frag- 

 ments of the •'black stone " which fell from the summit of the 

 cliff, a pile of which lay at its base, were often frozen into the 

 ice. and moved along with it. I then examined these fallen 

 blocks of amygdaloid scattered around me, and observed in 

 them numerous geodes coated with quartz-crystals. I have 

 no doubt that the hardness of these gravers, firmly fixed in 

 masses of ice, which, although only fifteen feet thick, are often 

 of considerable horizontal extent, have furnished sufficient 

 pressure and mechanical power to groove the ledge of soft 

 sandstone.* 



Stones are also striated by other agencies than moving ice. 

 Extensive avalanches and land-slides furnish conditions analo- 

 gous to those of a glacier, and might in limited and favor- 

 able localities simulate its results. In those larger geological 



* " Travels in America," first series, vol. ii, pp. 144-146. 



