388 pEOCEEDiNGs or THE GEOLOGICAL SOCIETY. [June 18, 



stone valley, and runs, by means of a deep and picturesque ravine, 

 tbe sides of which rise steeply to heights of 300 or 400 feet, right 

 across the Old Eed Sandstone ridge, which is there a mile and a half 

 broad. Having crossed the first ridge, it comes inlo another E. 

 and W. limestone valley, that of the Tallow outlier, where it receives 

 a large tributary from the west, called the Bride Eiver. It crosses 

 that valley, and cuts through another Old Eed Sandstone ridge by a 

 ravine like that of Dromana, but larger, the ridge being 3J m&es 

 broad, and rising in one point, called Carnglass, to a height of 

 650 feet, not far from the river. (See sections, PI. XX. figs. 1, 3 

 & 4). It then enters the smaller limestone valley of Clashmore, and 

 cuts across another smaller Old Eed Sandstone ridge into a fourth 

 limestone valley — that immediately above Youghal, and issues out into 

 Youghal Bay through a fourth ridge of Old Eed Sandstone, between 

 cliffs 100 feet in height, and through ground that rises to more than 

 double that altitude. 



This latter ridge is the termination of the one that bounds the 

 northern side of the Cork Yalley. 



The section, PL XX. fig. 1, shows the form of the main limestone 

 valley just above Cappoquin, before the river turns to leave it ; and 

 the section, fig. 2, shows its form 4| miles below Cappoquin, at the 

 part where the watershed occi-rs between the brooks flowing towards 

 the Dromana ravine and those flowing towards Dungarvan. The 

 latter exhibits, of course, the greatest obstruction that now exists 

 to the course of the Blackwater in the direction of Dungarvan, if the 

 ravine at Dromana were to be blocked up. 



Figs. 3 and 4 show the ravines at Dromana, 3 miles S. of Cappo- 

 quin, and at Carnglass, 4 miles still further south, along the course 

 which the Blackwater now follows. It is remarkable also that the 

 tide now flows up these ravines as far as Cappoquin, and that the 

 distance from Cappoquin by the valley to Dungarvan is only ten 

 miles, while through the ravines to Youghal Harbour it is 15 miles. 



If a dam only 80 or 90 feet high were now to be constructed at 

 the ravine of Dromana, the Eiver Blackwater, after forming a lake 

 on the flat lands about Cappoqain and Lismore, would inevitably 

 pour its waters along the valley into Dungarvan Bay, and excavate 

 a bed for itself in that direction, instead of flowing over and eating 

 away the dam at D^romana. 



This then is proof that it is impossible for the Eiver Blackwater to 

 have formed the ravines across the Old Eed Sandstone ranges since 

 the limestone acquired its present low level, or indeed anything 

 at all approaching that level. 



4. The Biver Lee. — The Eiver Lee issues from Lough Gougane- 

 barra, which has a height of 520 feet above the sea, and works its 

 way through valleys and hills of Old Eed Sandstone, and along one 

 little outlying limestone valley, until it breaks forth into the large 

 longitudinal limestone valley in which the city of Cork stands. It 

 there receives from the west a large tributary called the Bride Eiver 

 (like that in the Tallow Yalley), which has come in a straight course 

 trom Crookstown, at the western end of this long limestone valley, 



