XXXVl PROCEEDINGS OF THE GEOLOGICAL SOCIETY, 



teristic accumulations, especially in Yorkshire and Derbyshire, Mr. 

 Sorby has been able to determine within no very wide limits of 

 error, the probable depth of water, and the direction of the currents 

 by which the strata were deposited. In some cases the changes of 

 the direction of the laminae point to tidal action over and around 

 shallow sand-banks j in others a prevalent direction of wind is 

 recognized ; and in a majority of cases such a determinate set of 

 current as to assist in forming a map of the ancient sea-soundings. 



Thus in the Millstone-grit series of Yorkshire and Derbyshire a 

 very uniform general current from the north-east is recognized, 

 slightly interfered with by a tide setting from the north-west, and 

 by the action of surface-waves and wind- drift- current produced by 

 powerful westerly gales. During the deposition of the Magnesian 

 Limestone the sea appears to have been subject to a very decided 

 tide, rising and falling with great uniformity from W.S.W. to E.N.E., 

 amongst a number of shoals on which surface-waves stranded, chiefly 

 produced by easterly winds *. 



No part of the British Isles — no part of Europe, indeed — is more 

 remarkable than Ireland for great and repeated foldings of the 

 Palaeozoic strata of all ages. It suffices to look on Mr, Griffith's 

 map and sections to perceive the important effect which this structure 

 produces on the physical geography of Kerry, Cork, Waterford, and 

 other counties, — the ranges of hills, the inlets of estuaries, the coui'se 

 of rivers, the sites of population. In the same region slaty cleavage 

 is often prominent, and jointed structures prevail. Professors Jukes, 

 King, and Harkness have surveyed the joints and the cleavage m 

 many situations ; and Prof. Haughton has submitted these structures 

 as they occur in Waterford to a geometrical scrutiny. The district 

 selected for the purpose is the Old Red Sandstone tract of the coimty 

 of Waterford. In this tract are nineteen faults, reducible to two 

 pairs of rectangular systems. The bearings are — 



(«0E. 7°30'K. (f^ISr. 3°45'W. 

 (¥) E. 34° 22' N". (b') N. 33° 24' W. 



The average strike of the beds is E. 10° 46' N. The cleavage-planes 





* Eeport of British Association for 1858. 



