THE ERRATIC PHENOMENA. 403 



There is one feature in these phenomena, however, in which we 

 never observe any variation. The continuity of these lines is abso- 

 lutely the same everywhere. They are rectilinear and continuous, 

 and cannot be better compared than with the effects of stones or 

 other hard materials dragged in the same direction upon flat or roll- 

 ing surfaces ; they form simple scratches extending for yards in 

 straight lines, or breaking oif for a short space to continue again in a 

 straight line in the same direction, just as if interrupted by a jerk. 

 There are also deeper scratches of the same kind, presenting the 

 same phenomena, only, perhaps, traceable for a greater distance 

 than the finer ones. These scratches, instead of appearing like the 

 tracing of diamonds upon glass, as the former do, would rather assume 

 the appearance of a deeper groove, made by the point of a graver, or 

 perhaps still more closely resemble the scratches which a cart-wheel 

 would produce upon polished marble, if the wheel were chained, and 

 coarse sand spread over the floor. The appearance of the rock, 

 crushed by the moving mass, is especially distinct in limestone rocks, 

 where grooves are seldom nicely cut, but present the appearance of 

 a violent pressure combined with the grooving power, thus giving to 

 the groove a character which is quite peculiar, and which at once 

 strikes an observer who has been familiar with its characteristic 

 aspect. Now, I do not know upon what the assertions of some 

 geologists rest, that gravel moved by water under strong heavy 

 currents will produce similar eifects. Wherever I have gone since 

 studying these phenomena, I have looked for such cases, and have 

 never yet found modern gravel currents produce anything more than 

 a smooth surface with undulating furrows following the cracks in the 

 rocks, or hollowing their softer parts ; but continuous straight lines, 

 especially such crushed lines and straight furrows, I have never 

 seen. 



When we know how extensive the action of water carrying mud 

 and gravel is on every shore and in every water current, when we 

 can trace this action almost everywhere, and nowhere find it similar 

 to the phenomena just described, I cannot imagine upon what ground 

 these phenomena are still attributed to the agency of currents. This 

 is the less rational as we have at present, in all high mountain chains 

 of the temperate zone, other agents, the glaciers, producing these 



