374 ME. A. STRAHAN ON THE GLACIATION OF 



devoid of such lamination as is shown by clays deposited freely in 

 water, and thus present a strong contrast with the beds of laminated 

 clay or loam which sometimes accompany the sands and gravels. 

 The Eoulder-clays moreover contain twisted lenticular beds and 

 pockets of sand, the latter probably being disconnected portions of 

 a jumbled-up bed of sand. This mechanical disturbance is often 

 shared by the bed upon which a Boulder-clay rests, whether of sand 

 or rock : in the former case, the veins of loam and grit are 

 displaced, or so mixed up that the bedding is obliterated ; in the 

 latter case the more flexible strata are often bent, or the harder 

 ones striated. It seems, then, that not only is there a correspondence 

 in the direction of the drift-transportal and that of the striae, 

 but that the latter, themselves the direct work of ice, are found 

 only in conjunction with those beds of the drift which contain 

 evidence of ice-action. On these grounds alone there would be 

 a strong presumption that the same agent produced the striae 

 that distributed the Boulder-clay. This presumption is strengthened 

 by the fact that I shall now bring forward, that the striae in the 

 neighbouring borders of Wales, while showing an entirely different 

 prevalent direction, yet maintain the same connexion with the 

 associated drift-deposits. 



Paet II. 



The Welsh Border. 



The general parallelism exhibited by the striae of Liverpool is 

 less observable in those of the North- Wales border, probably 

 through their direction having been in many instances locally 

 influenced by the more pronounced configuration of the ground. 

 But though for this reason less importance must be attached to 

 individual striae, it is equally possible to generalize from a large 

 number. It may be stated that the N.N.W. direction, so common 

 about Liverpool, is exceptional in the neighbouring parts of Wales, 

 while the E.JST.E. direction observed in two instances only near 

 Liverpool becomes the prevalent direction on crossing the border. 



The localit}^ nearest to Liverpool in which striae have been 

 observed is on Pen-v-ball, near Holywell *, where they run N. 35° 

 E. and N. 40° E. At Pen-y-gelli they run E. and W., and E. 15° 

 N. On Cwm mountain the direction of striae, as observed by 

 Mr. Tiddeman, is :N'.E. and E. 33^" N., or E. 10° N. where observed 

 by Prof. Hughes ; while on Moel Hyraddug they are N.E. The 

 striae in these localities range from 600 to 1000 ft. above the 

 sea, and show an approximate parallelism ; they give an average 

 direction of E. 35° JN'., and thus agree closely with the cross striae 

 at Liverpool, which run E. 22° N. and E. 30° N. 



Further south, I have observed striae running E. 18° ^. at an 

 elevation of 1100 feet on Gwern-to, a hill on the north side of the 



* First observed by Mr. G. W. Shrubsole, F.G.S. (see Morton, Proc. Liverpool 

 Qeol. Soc. sess. 17, 1875-76). 



