142 Notes from Correspondents. 



bores at low water, and that its holes run at various angles to 

 the horizon, one hole very often ciitting through another at nearly- 

 right angles. The holes in inland or supra-marine limestone dis- 

 tricts are frequently bored through each other. Mr. Mackintosh is 

 of opinion that the PJiolas can bore upwards ; it is certain that the 

 Saxicava can do so. 



In different parts of England and Wales Mr, Mackintosh has 

 observed great numbers of borings in limestone rocks, at various 

 altitudes above the sea-level. They seldom ran vertically upwards 

 from the underside of a stone in situ, but were not infrequently hori- 

 zontal, and sometimes directed at a small angle downwards. In no 

 instance has he found a live snail in any of these holes. All his 

 observations tend to militate more or less against the theory that the 

 holes have been excavated by snails. 



Denudation of the Lake Districts. — Me. Mackintosh offers a 

 few remarks respecting Mr. J. C. Ward's article in the January 

 number of the Geological Magazine (p. 14). The assumed proba- 

 bility that the sea, during the Glacial submergence, was an im- 

 movable frozen mass (an indispensable prop, as he considers, to the 

 subaerial theory), is opposed by four facts : — 1. The proximity of 

 the Lake District to the southern border of the ice-covered region ; 

 2. The diminution of cold consequent on the diminished extent of 

 high land, when the area of Great Britain was reduced to the condi- 

 tion of small islands ; 3. The intensity of marine action, proved by 

 the enormous accumulations of drift in areas contiguous to the Lake 

 District ; 4. The transportation of boulders from one part of the 

 Lake District to another, and from that district to surrounding areas, 

 proving the activity of oceanic currents. 



Mr. Mackintosh objects to the existence of fallen debris (or screes) 

 on steep slopes being brought forward as a proof of sub-aerial origin 

 of valleys. The valleys existed before the debris began to fall, and 

 now they are in course of being obliterated. 



The carrying powers of the streams in the Lake District is in 

 most places truly insignificant when compared with the rate of ac- 

 cumulation of screes. 



Mr. Ward disputes his assertion that the escarpments generally 

 face the east, south-east, or north-east. Mr. Mackintosh remarks 

 that the term escarpment ought not to be confined to the outcrop or 

 upcrop side of a ridge, because this side is not always marked by the 

 most regular, steep, and continuous slope. He would like to be 

 informed of the existence of a long, steep, continuous slope, with or 

 without cliffs, facing the north-west, west, or south-west, to the east 

 of a line drawn from Blackcombe to Skiddaw Forest, with, the ex- 

 ception of the Wallow Crag escarpment (which nearly coincides 

 with a fault), and Loanthwaite Crag. The greater part of the Lake 

 District lies to the east of this line. Two or three exceptional cases 

 might be found, but Mr. Mackintosh has not met with any. 



To the west of this line, as he has elsewhere remarked, the prin- 

 cipal escarpments face various points of the compass. 



