PERCHED BLOCKS AND ASSOCIATED PHEJfOMEXA. 531 



Ingleborough House and Austwick, on the elevated ridges of Feizer, 

 on the summit of Giggleswick Scar, and at greater heights on the 

 rugged mountain over Stainf orth, Langcliffe, and Settle, and eastward 

 of this place toward the summit of the road to Malham Cove. The 

 greatest elevation reached by the slaty rock in situ in the district is 

 about 1160 feet in Moughton Fell, the limestone there rising over 

 it to the height of 1404 feet. It is at about the same height under 

 the bare limestone of Long Scar. The hills on to which it has been 

 drifted southward do not in general rise so high as this ; but Feizer 

 is about 30 feet higher, and the point on the hills over Settle which 

 is reached by the blocks, in considerable number and of great magni- 

 tude, is not less than 1350 feet, nearly 200 feet above the highest 

 part of the native rock. Still more singular is the fact that the 

 limestone of Long Scar, the hill which rises over the slate to a height 

 nearly the same as that of Moughton Fell, is covered by very many 

 of these blocks brought from below, and scattered on the surface to 

 a height of not less than 1260 feet. The blocks are very often 

 perched : show no marks of abrasion ; no other drift matter is with 

 them ; they are collected sometimes into small groups ; and they 

 may be regarded as having been uplifted and floated by ice, and 

 dropped on surfaces which had been swept by currents clear of other 

 loose matter. 



" In lower ground, to the southward, westward, and eastward, the 

 slaty blocks have been carried very much farther ; in this case they 

 are no longer solitary, but mixed with other sorts of detrital matter, 

 and occasionally show marks of attrition in water, which they 

 never do on the high limestone hills (see the Lithograph). " 



In the figure referred to (pi. v. fig. 3) he represents the block as 

 perched on an elevated part of the limestone, but he does not seem 

 to have observed the glaciation of the top of the pedestal ; nor does 

 the explanation that the surrounding part of the limestone had 

 perished since the deposition of the boulder where now found seem 

 to have occurred to him. 



In a paper read before the Geological and Polytechnical Society 

 of the West Riding of Yorkshire in 1867, I drew attention to these 

 facts as follows : — 



" About a mile N. of Austwick, there are some very interesting 

 points connected with glacial phenomena and subsequent denu- 

 dation. Resting on the mountain-limestone plateau of ISTorber, 



there are a number of large blocks of Silurian grit 



These have been forced along from beds at a 



lower level in Crummack valley, and left often on a bare table 

 of limestone. Now, as every one must have observed who has 

 walked over these limestone hills, the rock is jointed in all direc- 

 tions, and the water which falls on the limestone, whether as rain, 

 or as small streams, collected on the overlying Yoredale rocks and 

 drift, disappears in the crevices of the limestone. The result is, that 

 tbere are no streams running over its surface, and all the water 

 which reaches it at any distance from the shale or drift boundary, 

 is the rainfall on that particular spot. Well, this rainfall has been 



