1862.] JUKES — DRIVER-VALLEYS. 387 



The Old Eed Sandstone ridge which rises immediately to the 

 south of this valley, invariably presents to it a steep slope with an 

 undulating, but generally unbroken summit-ridge. The bottom of the 

 limestone valley rises very slowly as we proceed from Dungarvan 

 towards the interior of the country, until we arrive at its summit- 

 elevation of 550 feet on the borders of county Kerry; and the 

 average height of the summit of the ridge to the south of it increases 

 in at least an equal ratio. 



The mean height of the ridge in Waterford is about 400 or 500 

 feet above the sea, with summit-elevations rising to 780 feet, while 

 the highest parts of the limestone attain at one point only to so 

 great an elevation as 200 feet. Between Permoy and Mallow, where 

 the summit-elevations of the limestone on the plain of Castletown 

 Eoche rise to 270 feet, the Old Eed Sandstone attains, in the Nagie 

 Mountains, to 1340 feet in height. Between Millstreet and Kil- 

 lamey, where the watershed of the Blackwater and Flesk Eivers 

 occurs at 550 feet, the Old Eed Sandstone is an unbroken moun- 

 tainous ridge, with summits, such as Caherbarnagh and the Paps, 

 between 2200 and 2300 feet high. Beyond this, where the level of 

 the limestone descends again to the Lower Lake of Killarney, the Old 

 Eed Sandstone forms the range of which Mangerton, the Eeeks, 

 and Carantuohill (3414 feet, and the loftiest peak in Ireland) are 

 the summits. 



The crest of this ridge, between Cappoquin and Mangerton, is in 

 a few places deeply indented by transverse valleys or gaps, of which 

 the level-floored Pass of Glenflesk, leading from Killarney out into 

 the Kenmare valley, is one of the most remarkable examples. The 

 valley through which the Cork Eailway runs from Mallow is the next 

 greatest depression; and the valley soufe of Fermoy is the third. 

 In Glenflesk a very little deeper cutt.'ng towards Morley Bridge 

 would divert the waters of the Plesk into the valley of the Eoughty 

 Eiver, and allow of the drainage of some of the ground on the north 

 of the ridge flowing right through it down to Kenmare. This deeper 

 cutting, however, has not taken place ; and the range preserves its 

 character of a watershed between the rivers on the north and those 

 on the south all the way from the headlands of Kerry to those south 

 of Dungarvan Harbour, with the very remarkable exception of the 

 Dromana gorge, south of Cappoquin, which I am now about to 

 mention. 



The Eiver Blackwater is first formed by brooks draining the high 

 Coal-measure ground near King Williamstown, on the borders of 

 Kerry. It runs due south to the foot of the high land near Caher- 

 barnagh, which deflects it at right angles, to the east, down the 

 narrow limestone valley before mentioned. It runs eastward down 

 this, past Mallow, Fermoy, and Lismore, for a distance of fifty-five 

 miles to Cappoquin. Beyond Cappoquin the valley is continued out 

 to Dungarvan Harbour in the same straight line, with the same general 

 low level, and with the same Old Eed Sandstone ridges on both sides 

 of it. Instead of following this obvious course, however, the Eiver 

 Blackwater turns suddenly at Cappoquin due south, crosses the lime- 



VOL, XVIII. — PART I. 2d 



