464 Ecvieivs — Nicholson's Essay 



they are now, and similarly in the case of the Permian, we must 

 have some explanation why a deposit, estimated at 8000 feet, in a 

 valley bounded by hills between 2C00 and 3000 feet only, should 

 not have extended over those hills, unless the Lake Mountains 

 were at least 5000 feet higher relatively to the present base of the 

 Permian. Moreover, if the Carboniferous deposits never extended 

 over the Lake Mountains, the Permian conglomerates should contain 

 more Silurian fragments. 



On the whole, the evidence rather goes to show that the Carboni- 

 ferous deposits did extend over the Lake District, and the Permian 

 was only prevented from resting on the Silurian Eocks also, because 

 the Carboniferous intervened. We have, however, the fact that in 

 the north-west of England, there was from a very early period an 

 irregular boss of old rocks which affected original deposition and 

 subsequent denudation. 



It does not seem clear why the author objects to " the theory that 

 the older rocks of the Lake District have been raised along an axis 

 of elevation running across the district in an E.N.E. and W.S.W. 

 direction," (p. 2). This is only another way of saying that the 

 older rocks come up along a line running in the direction named, and 

 that the newer rocks crop out in order on the north and south of it. 

 Surely this is a fact (see pp. 20 and 21) ; and moreover, one which 

 does not involve any theory as to the direction of the faults, 

 and does not imply that there are not many folds parallel to the 

 principal line of upheaval. There is certainly more than a " single 

 line of elevation," and the group of mountains can only be called a 

 dome-shaped mass in reference to the general surface-configuration. 



The evidence on which he grounds his view that the Silurian high 

 ground extended from the Lake District to the Isle of Man, in Car- 

 boniferous times, does not seem quite satisfactory, for the denudation 

 that could have removed that quantity of Silurian rock between the 

 Carboniferous and Permian times could have removed the same 

 quantity of Carboniferous strata in the same time or less. It seems 

 more probable that this great denudation was principally effected in 

 the vast unrepresented time between the close of the Silurian and the 

 commencement of the Old Red Conglomerate age. 



The question of the faults of the Lake Country is one of great 

 interest. The author has pointed out the direction and circumstances 

 of the principal ones, and says that they may be classified in two 

 great systems according to their direction and age. Faults from the 

 nature of the case are difficult lines to draw, except where rocks of a 

 different character are thrown together. As the author has pointed 

 out at the end of his introduction, the smashed rock was a line of 

 weakness along which rivers, glaciers, and all denuding agents have 

 worked. Hence great faults generally coincide with valleys, and 

 are covered up by drift and allmvium. The author has, perhaps, 

 generalized too far with the data in his possession. For instance, 

 the Craven and Penine faults are not each of them one great fault, 

 but a set of nearly parallel faults of various age, the downthrow of 

 some being on one side, of others on the other. One of the Craven 



