1862.] JUKES — ^MYEE-VALLEYS. 395 



It is obvious that this proposed explanation involves the supposi- 

 tian that, after the production of the land-surface over which the 

 Brinny first commenced to run, all the subsequent denudation of the 

 country and the excavation of all the valleys have been the result of 

 atmospheric agencies alone. 



b. Biver Lee. — About 3 miles to the east of Cork there issues from 

 the Old Eed Sandstone ridge that lies to the north of that valley a 

 large brook, formed by the junction of several minor streams on the 

 higher parts of the ridge. (See Map, PL XIX.) It cuts deeply down 

 into the Old Eed Sandstone, forming picturesque glens, the lowest 

 and deepest of which is called Glanmire. 



Nearly opposite the mouth of the Glanmire Valley, but a little to 

 the E. of it, is the cut across the limestone ridge which separates 

 Blackrock from the Little Island, and leads into Lough Mahon. 

 Turning still further to the S.E. down the central channel of Lough 

 Mahon, which alone has deep water in it at low tide, we are led to 

 the ravine, caUed Passage West, that cuts across the Old Eed Sand- 

 stone ridge to the S. of the Cork Yalley ; and, passing through that, 

 and turning again to the east, we are brought into Cork Harbour. 



About 8 miles to the east of the Glanmire YaUey, we arrive at 

 another precisely similar deep glen issuing out of the Old Eed Sand- 

 stone ridge at Ballyedmond, and bringing the Owenacurra and other 

 brooks from the high land on the north on to the limestone valley 

 about Middleton. This brook crosses the limestone valley at Middle- 

 ton, and runs into the eastern end of Lough Mahon ; and turning a 

 little to the west, we are led by its channel to the ravine of Passage 

 East, through which we also arrive at the basin of Cork Harbour. 



The deep-water channels from the West and East Passages unite in 

 Cork Harbour, to the east of Queenstown, and lead out thence due S. 

 to the ravine which forms the entrance to the harbour and conducts 

 us into the open sea. 



When once pointed out, the relation between these lateral brooks 

 flowing from the dominant ridge on the north, and the north and 

 south cuts through the lesser ridges on the south, becomes so obvious 

 that I think the belief must be at once impressed on the mind that 

 the latter are only the continuation of the former. 



As in the case of the Brinny, I believe that on some former surface 

 considerably above the present one, a river, made up, like all other 

 rivers, of a union of lesser streams, ran down the slope from N. to S. 

 over Glanmire, and that, as it wore down its channel, it intercepted the 

 western drainage of the Lee which was poured into it down the ever- 

 enlarging longitudinal valley. The united waters were always turned 

 down the transverse ravines, because, at whatever rate the ground 

 in the longitudinal valleys sank, the erosion of these rivers was 

 able to keep the bottom of the ravines sufficiently below it ; while 

 other brooks, being unable to effect this, were ultimately drawn 

 down into the longitudinal valleys, and their water carried out 

 to the ravines. As before, this must have been an atmospheric 

 action upon dry land. That the land happens now to stand at such 

 a level that the sea flows into the part occupied by Cork Harbour, no 



