PERCHED BLOCKS AND ASSOCIATED PHENOMENA, 



529 



of lichen and moss, while the surrounding surface had been eaten 

 away. 



In this case, however, we must be especially careful not to 

 measure the time which it has taken to reduce the surrounding 

 limestone by the height of the pedestal, as this is obviously not due 

 to the rain only, but also and chiefly to the action of the damp soil 

 and vegetation, which has covered it all, up to the very base of the 

 pedestal on which the boulder rests. 



On Farleton Knot the boulders, instead of being of Silurian, are 

 of massive Mountain Limestone. They appear to have been gene- 

 rally derived from a thicker bed than that on which they rest. Such 

 a bed occurs a little below the horizon on which they are found, in 

 a part of the series which crops out just over the brow of the hill to 

 the north. The slope of the hill generally coincides with the surface 

 of the beds, but here and there the surface is seen to have been 

 planed off irrespective of the bedding. 



Fig. 2. — Boulder of Mountain Limestone on a Pedestal of Mountain 

 Limestone, Farleton Knot, Kendal. 



This boulder measures 4 ft. 7 in, in greatest length, and 3 ft. 4 in. in height. 

 The pedestal on which it stands rises about 1 foot above the surrounding 

 grass-covered limestone. The strise on the pedestal run approximately 

 N.E. and S.W. 



The pedestals are here rather lower than those of Norber Brow or 

 Cunswick Tarn, being not often more than from 3 to 7 inches high. 

 Some, however, are as much as a foot high, but only in those cases 

 where the growth of vegetation along the master-joints had obviously 

 helped the work. In many cases on Farleton Knot the boulders 

 seem to have protected a somewhat larger surface of the limestone 

 than that immediately below them ; but the part of the limestone so 

 preserved was always on the side away from the south-west wind. 

 It seemed also that the boulders and pedestals were breaking down 

 over the whole hill, and here and there one could see a round bump, 

 from 3 to 5 inches high, rising above the general level of the 

 limestone and marking the place where a boulder had formerly been 

 perched. Often the boulder was seen close by, whether pushed off 



