92 THE RELATIONS BETWEEN FAULTS, OPEN JOINTS, 



less re-excavated. Dana suggests 1 that large rivers 

 may have flowed during all the glacial period in the 

 valleys under the ice-sheets, which appears highly 

 prohable, in which case many of the present valleys 

 may never have been occupied by drift. Or even if 

 such rivers did not previously exist, after the ice 

 began to disappear the valley would be kept clear, as, 

 " sooner or later, the water from the melting ice, 

 descending through the crevasses or other openings, 

 would have made streams in all the valleys, even 

 those now dry." " The melting would have gone 

 forward with increasing haste as -the thickness of 

 the ice lessened ; and all the streams would thereby 

 have been flooded far beyond modern experience, and 

 consequently the work of transportation and deposi- 

 tion would have been vastly accelerated." 



In the country lying about the junctions of the 

 Nore, the Barrow, and the Suir (parts of the Cos. Car- 

 low, Kilkenny, Waterford, and Wexford), there are 

 many deep, narrow, and for the most part, " rock- 

 valleys," they having been evidently formed in the 

 rock of the country, their slopes being in nearly all 

 cases meteoric drift, due to subsequent weathering of 

 their cliffs. 2 Glenmore, the valley by which the 



i American Journal of Science and Arts. Third Series. Yol. v., 

 p. 200. 



a When the base of a cliff has been deserted by the sea, it is gradu- 

 ally modified into a slope. Prior to the year 1846, the north portion 

 of the estuary of Wexford Harbour was bounded on the north by 



