224 DK. R. ANGUS SMITH ON CAUSES 



heap to heap was a good mode, but caused a greater exertion 

 than mere walking causes. This effort and the attempt to 

 walk in the furrows (the least pleasant method) brought 

 the fact before my mind very strongly. I could see no 

 good reason for the phenomenon, although I imagined frost 

 to be the beginning ; and I also imagine that 1 have seen 

 the circumstance mentioned in a periodical. However, I 

 have asked two eminent geologists, and they have not been 

 able to direct me to any account of such a circumstance. 



Walking over the Island of Videy I saw the same state 

 of surface in many places (not in every place) ; and there 

 was a less regular form of it close to Reikjavik, and in cer- 

 tain places a few miles out. It was a daily wonder until, 

 on wandering slowly on a pony towards Ellida Vatn after 

 having gone to the right of the road to the Geysers, I saw 

 at the side of the track small cracks in the soil forming 

 figures about the size of the little mounds spoken of. The 

 soil on the district now traversed had no grass, and it was 

 closely allied to a fine gravel and had little cohesion. These 

 figures were numerous ; and the cracks were very narrow, 

 scarcely half an inch in most cases, weaving a network of 

 great regularity. 



Then it came to my mind still more strongly that the 

 action of frost must be at the root of it. In our own 

 country, after thaws, we find walks with some gravel and 

 a similar amount of cohesion as at Iceland breaking up in 

 such a manner that some portions rise 2 or 3 inches ; and 

 there being nothing present to fill up the void caused by 

 the separation from the rest of the surface, a crack or 

 empty space is the consequence. With us this is done in 

 a most irregular manner : there is no distinct form ; and 

 all the pieces are small, a few inches at most. In this 

 bare field in Iceland the size was some 2 to 3 feet in 

 length and less than 1 broad; and there was no rising 

 apparent, only the separation and the crack between the 



