98 Proceedings. 



the small specimens some which contained fragments of 

 rhyolite lava enclosed in andesite, and as such an associa- 

 tion is of rare occurrence in Britain, he thought the 

 fact that andesites and rhyolites were to be seen in the 

 country about Honister and Coniston, might be accepted 

 as evidence of the derivation of the boulder from that part 

 of the Lake District. He had indeed seen specimens which 

 were indistinguishable in appearance from the example 

 under consideration. The specific gravity of the rock was 

 about 275, which would indicate a weight of about i7olbs. per 

 cube foot. The weight of the boulder might be taken as 

 between 20 and 30 tons. He added some observations 

 upon the question of a vertical circulation in the glacier-ice, 

 which might possibly account for the fact recorded by Mr. 

 J. G. Goodchild that transported blocks have been found at 

 an altitude of 1,000 feet above the parent rock, though at a 

 distance of 5 or 6 miles. 



Mr. Faraday alluded to the perched blocks on Norber, 

 a spur of Ingleborough, and suggested that the Craven 

 district was worth considering as a possible source of 

 travelled blocks found in this neighbourhood. 



