36 DR T. J. JEHU ON 



Abersoch village stands is grassed over, but marine-like sands appear wherever the 

 ground is dug into, and apparently these sands mantle the land around the village. 

 Drift is not again exposed along the coast until we pass east of Mynydd Tir-y-cwmmwd. 

 Llanbedrog. — Between Mynydd Tir-y-cwmmwd and Careg-y-defaid, both of which 

 are rocky and formed of felspar porphyry, the cliff consists of Drift deposits, and good 

 sections are exposed for a distance of over a mile. Stiff dark brownish Boulder Clay is 

 seen on the foreshore at the west end of the bay, and at one place this clay forms the 

 lower part of the cliff. This is the Lower Boulder Clay, and it underlies the Sand and 

 Gravel series which forms the cliff all along the bay. The cliff has a very uniform 

 height of a little over 30 feet. The sands and gravels are stratified, and occasionally 

 show oblique bedding. The sands are orange-coloured and somewhat ferruginous ; they 

 yielded no shell-fragments. So in this bay we have represented 



2. The Intermediate Sands and Gravels. 



1. The Lower Boulder Clay. 



On the beach, boulders of Carboniferous Limestone were seen and of granites from 

 the Dalbeattie area ; very common also were boulders and pebbles of the reddish- 

 streaked rhyolite which is so often found scattered about Lleyn. 



From Careg-y-defaid to Pwllheli the coast is bounded by sand dunes. An old 

 coast-line can be traced some distance inland in the shape of a cliff which is now grassed 

 over. This old cliff is separated from the dunes by flat land some of which is marshy. 

 Sand dunes again border the coast-line east of Pwllheli, as far as the felspar porphyry 

 promontory of Pen-y-chain. 



The greenstone mass of Careg-y-rhimbill opposite Pwllheli is being rapidly de- 

 molished by quarrying operations, but its summit presents a moutonneed aspect. 



At Pwllheli, in connection with the Harbour Works, a boring was made in the estuary, 

 and the following deposits were traversed : — 



3. Mud — 6 inches. 



2. Ballast and sand — 4 feet. 



1. Stiff blue clay — 8 feet. (The bottom of this clay was not reached.) 



East of Pen-y-chain, cliffs composed of Drift deposits are again met with and are 

 being eroded by the sea. The best sections are displayed between Afonwen and Afon 

 Dwyfor. 



Afonwen to Afon Dwyfor. — On the Geological Survey Map (1 inch to the mile) 

 these cliffs are marked as consisting of " stratified sands, clay, and gravel." The main 

 deposits exposed along this stretch of coast are : — 



2. Upper Boulder Clay and Rubble Drift. 

 1. Sands and Gravels. 



The Lower Boulder Clay of the Lleyn promontory is not seen here. The sands are 

 often well bedded, the gravels generally coarsely bedded. At places the sands show 





