THEIR CONTENTS. 301 



a boulder so large as nearly to half fill it : such a stone 

 is always much polished and nearly round) ; then, next 

 to the sides of the ' Gryta,' stones of all sizes, and 

 similar to them in shape. Near to the bottom of the 

 ' Gryta,' again, are almost always found stones varying 

 from 2 to 10 inches in diameter, worn away to nearly 

 perfect spheres. Some, however, are egg-formed, or almost 

 oval. As a general rule, the boulders are smaller, and the 

 gravel and sand finer, towards the bottom. At the very 

 bottom the sand is invariably worn to a fine powder. The 

 ' Grytor ' I am describing, it is my full belief, have never 

 before been excavated. Everything proves they ai'e in 

 precisely the same state as the ice or glacier period of 

 Sweden left them. 



" It must be borne in mind that when the ' Grytor ' 

 were under formation, the surface of the rocks was also 

 wearing away, so that they could never wear deeper than 

 in a given ratio, depending on the wearing of the surface 

 of the rocks above. 



" It is now many years ag.0," Mr. Keiller further 

 remarks, " that I first made acquaintance with the ' Elf- 

 Grytor.' This was at Surtur. The formation of these 

 very remarkable cavities struck me greatly, and I have 

 since made them a study. Wherever I have travelled in 

 Sweden, I have always been on the look-out for ' Grytor,' 

 and carefully examined the localities ; and I have now 

 become so experienced that I can to a certainty point 

 out not only where one is to be found, but state with 

 tolerable accuracy its depth and diameter ; as also whether 

 it has been bored or worn, so to say, in the form of a 

 right-hand or of a left-hand screw. If we observe the 

 current of a river, we find that on the one side all the 

 eddies and vortices are found in the direction of the 

 stream ; or, on one side right-hand eddies, and on the 

 other left-hand eddies and vortices." 



