18 DR T. J. JEHU ON 



Sir Andrew Ramsay, in his Survey Memoir, "The Geology of North Wales" 

 (2nd ed., 1881), makes only occasional references to the glaciation of Lleyn. Describing 

 the district, he says : " Like Anglesey it partly consists of metamorphic rocks, which 

 are supposed to be of Cambrian age, and of Lower Silurian strata, through which 

 numerous bosses of rock protrude of a syenitic and dioritic character. Some of these 

 are of great extent, and in Bwlch-mawr and Moel Penllech, Yr Eifl or The Rivals, Cam 

 Bodvean, Mynydd Nevin, Cam Madryn, Mynydd Mynytho, Mynydd-y-Rhiw, and other 

 minor heights, they generally rise high above the plain of glacial drift that shrouds so 

 much of the country, and thus form the loftiest hills of the district. The stratified 

 rocks, indeed, generally lie in ground so low, and, except on coast cliffs, they are mostly 

 so obscured by sands and marine boulder clays, that it is difficult to make out the 

 details of this stratification" (p. 206). Again he states (p. 221) that "from the heights 

 of Yr Eifl the promontory of Lleyn, but for the chain of Puys, looks like a mere plain." 

 He mentions "an angular breccia of post-Tertiary date resting on the slaty strata" at 

 Porth Ceiriad and underlying the Drift deposits (p. 208). Beds of angular breccia are 

 also noted as occurring in Aberdaron Bay (p. 211). With regard to Bardsey Island he 

 observes that " like the mainland the country has been moulded by ice during the Glacial 

 period, but the mammillated rochcs moutonnees have since been roughened by weather" 

 (p. 212). He describes the ice-sheet which overspread Anglesey as continuing "its 

 onward course to some unknown distance, for on the ice-ground rocks above the sea- 

 cliff of Trwyn-y-tal, a mile north of the seaward flank of Yr Eifl, well-marked striations 

 are seen pointing towards the Straits 43° north of east " (p. 273). 



In Ramsay's Physical Geology and Geography of Great Britain (6th ed., 1894, 

 p. 246), mention is made of the occurrence of shell-bearing deposits in the district of 

 Lleyn. It is also stated (p. 248) that " at various levels on the low ground between 

 Carnarvon and Criccieth there are extensive deposits of sand and gravel, well stratified, 

 and much resembling those of Moel Tryfan, but apparently without shells." These 

 are overlain by boulder beds. He held the view that there had been two epochs of 

 glaciation in Wales separated by an epoch of submergence during which the land was 

 drowned to a depth of 1400 feet or more. 



Mr Carvill Lewis in The Glacial Geology of Great Britain and Ireland, 1894 

 (p. 355), states that " deep till, with many large boulders, covers the land, and makes the 

 moorland extending from Afonwen to Carnarvon." He also noted the peat at Ynysand 

 Pant-glas and the " hills of till " at Brynkir ; the " very large beds of coarsely stratified 

 drift, full of large boulders and knob-like in shape," occurring near Penygroes. " All this," 

 he concludes, "probably belongs to the great ice-sheet, not to the Welsh glaciers." He 

 gives a Glacial Map of England and Wales in which the margin of the northern ice is 

 depicted as reaching North-Western Lleyn but leaving the southern part of the pro- 

 montory free. In common with many other geologists, Mr Carvill Lewis denied that 

 the so-called "Intermediate Sands and Gravels" indicate a submergence of 1400 feet. 

 He regarded the high-level shell-bearing sands, such as those of Moel Tryfan, simply as 



