290 Bonney — Glacial Action near Llandudno. 



boniferous limestones, but crumbles away more like indurated clay. 

 It can be found in situ on a very slight eminence in the neighbour- 

 hood. I could not discover any distinct trace of moraines ; which, 

 indeed, could hardly be expected, owing to the absence of peaks. 

 Probably in the glacial epoch the Great Ormeshead was a low island 

 with its undulating icy cap (of no great thickness) broken here and 

 there by a scarcely projecting ridge of rock. 



The precipitous sides of the Great Ormeshead appear to me to 

 bear distinct traces of the action of the sea in the form of steep lines 

 of cliff with hollows and furrows at intervals. Its eastern face con- 

 sists of two well-marked cliffs, separated by a sloping talus thinly 

 covered by a reddish marly clay containing many angular fragments 

 of limestone. The base of the lower cliff is washed by the sea ; and 

 it is instructive to compare the wave marks on it with those exposed 

 some 200 feet or more above in the face of the upper cliff. Shells of 

 Patella vulgata and Littorina littorea are not rare in the clay of the 

 talus by the footpath near Pen-trwyn. 



On the S.E. of the Great Ormeshead is a lower eminence called 

 Pen-y-Dinas (on which are the remains of a British fort), separated 

 from the main mass by a hollow, which opens out on the one side 

 towards the town of Llandudno, on the south, and on the other to the 

 sea, on the east. A deposit of reddish marly clay, with angular 

 fragments of limestone, covers the lower parts of this, and is of con- 

 siderable thickness in the neighbourhood of the sea. In the upper 

 part of the hollow, near Gwydfyd Farm, is a bed or pocket of light- 

 buff sandy marl, mixed with fragments of chert, which has been 

 described by Mr. Maw in an interesting paper in this Magazine 

 (Vol. II. p. 200). 



This is covered by the clay, which is here from two to three feet 

 thick, and contains shells in considerable numbers. In a few minutes 

 I collected many specimens of Patella vulgata, Littorina littorea, 

 Mytilus edulis, with an ostrea (both valves), and three separate 

 valves of Tapes (pullastra?) . This clay, both here and elsewhere, 

 appears to have been deposited after the ground had pretty nearly 

 assumed its present configuration, and to have not undergone much 

 denudation during the process of upheaval. 



Again, on the S.W. side of the Great Ormeshead, just beyond the 

 house at present belonging to the Dean of Christchurch, we find, 

 below the fine line of limestone precipices, a steep talus, the lower 

 part of which has been destroyed by the sea, and a cliff of soil and 

 clay thus formed. In the upper part of this cliff, beds of marine 

 shells occur with partings of dark browTi soil ; as, however, I con- 

 sider these to be kitchen -middens, I pass them by on the present 

 occasion. Below these we have the following section : (1) reddish 

 clay, with many angular fragments of limestone and rolled trap- 

 pebbles — about 2ft. ; (2) reddish sand, yellower in upper part, with- 

 out pebbles — about 3ft. ; (3) talus of fallen sand and clay — about 

 4ft. ; (4) the pebbly shore. As the cliff is followed to the N.W., (1) 

 is seen to thicken out rapidly and form a cliff some fifteen or twenty 

 feet high, in which are many large angular limestone boulders. 



