SOUTH LAIv^CASHIKE, CHESHIRE, AXD THE ^VELSH BOEDEE. 371 



markings to glaciers descendiDg the valleys. In the same year 

 (1877), Mr. Morton * published a complete list of all the striae 

 known up to that time, and after considering the divergence of 

 direction over a small area, and the partial occurrence of striated 

 surfaces, rejected the land-ice theory in favour of drifting field-ice 

 carried by tidal currents. In this year also t I observed striae in 

 the neighbourhood of St. Helens bearing W. 30^ N. and W. 33° N., 

 and in four instances near Widnes bearing W. 8° jS". ; as also a 

 remarkable striated surface at the Pool Hall Rocks, near EUesmere 

 Port, between tide-marks, where the striae ran ]^. 43° W. 



Omitting the cross striations observed at Bootle and Flaybrick 

 HiU, the above-named scratches (see Map, fig. 1) show an appproxi- 

 mate parallelism. Those in the immediate neighbourhood of Liver- 

 pool and Birkenhead, forming a group of fourteen in number (not 

 including the single oblique groove observed by Mr. Morton in 

 jS'orth Hill Street J), have an average direction of ]^. 28° W., with an 

 extreme variation of 27°. A line drawn in this direction through 

 Liverpool would pass about halfway between the coast of Cumber- 

 land and the Isle of Man, and coincide approximately with the 

 direction of the channel of the Mersey at Liverpool. 



The Pool Hall striae also coincide in direction with the river, which 

 here begins to bend to the east ; and the same observation may be 

 made with regard to the striae about Widnes. They were no doubt 

 influenced in their direction by the Keuper-Sandstone hills, which 

 rise abruptly from the plain on the south side of the valley of the 

 Mersey. But as the same tendency to a deflection towards the east 

 is shown at Thatto Heath and St. Helens, though to a less degree, 

 there would appear to be a general change in the direction of the 

 glaciation, independently of local causes of deflection, from j^. 

 20°-30° W. in Liverpool to about jN'.W. further inland. It may 

 here be remarked that striae have been observed at Manchester 

 running N. 40° W. § 



Two cases only of striations having a totally different direction 

 have been observed near Liverpool — in one case at Bootle, run- 

 ning E.X.E., by Mr. Eeade, and in the other at Plaj-brick HiU, 

 Birkenhead, running E, 30° N., by Mr. Mackintosh. A line drawn 

 through Liverpool in the mean direction of these striae passes 

 nearly through Snowdon, and is almost exactly at right angles to 

 the mean direction of the first-described set. 



In the diagram, fig. 2 (p. 372), the whole of the striae described 

 above are represented in their true directions ; the preponderance of 

 those in the north-west quarter of the compass and the general 

 parallelism of those in the immediate neighbourhood of Liverpool are 

 sufficiently obvious. 



There is unfortunately very little evidence afforded by the ap- 

 pearance of the scratches themselves as to whether the glaciation 



* Proc. Liverpool Geol. Soc. sess. 18, 1876-77. 



t Geol. SuTTey Memoir, ' On the Superficial Deposits of S.W. Lancashire/ 

 p. 47. J j Proc. Liverpool Geol. Soc. sess. 18, 1876-77. 



§ J. Plant, Trans. Geol. Soc. Manchester, vol. vi. 



