DEPOSITS AND ELEVATION. 11 



Diganwy Hotel, past Bryngosol, to the main road. In 

 the west cliflP, fragments occurred of 



Mya truncata. Cardium edule. 



Tellina solidula. Mytilus edulis. 



Mactra. Buccinum undatum. 



Collectors must be careful not to confound with genuine 

 fossils from this bed the weathered but not worn fragments 

 of Mytilus, Cardium, and Willow-pattern, which not un- 

 frequently occur on the face of this section, and are due to 

 tillage of the surface and some rain -wash. 



This seems to be a true boulder-clay. It is just dis- 

 ting-uishable at Llandudno from the bed below, whose 

 Astarte it does not appear to share. The bed with similar 

 fragments occurs at a 70-feet elevation above the bath- 

 house. I may mention a very fine section of it near some 

 white cottages on the road-side, at the eastern foot of 

 Penmaenbach, to the west of Conway, showing, besides the 

 usual promiscuous assortment, one fine horizontal bed of 

 large boulders high up in the clay clifi". From the same 

 bed, at a brickfield at the foot on the west side of Penmaen- 

 bach, I have obtained worn shells of Littorina littorea and 

 Fusus antiquus. Both of the Llandudno beds are repre- 

 sented, as Mr.Binneyhas pointed out, in the Blackpool cliff's. 



The greater variety of species which figures in the Lan- 

 cashire list^ may be attributed to the occurrence there of 

 larger beds of sand and shingle, apparently deposited under 

 littoral (or at all events shallow- water) conditions very dif- 

 ferent from, and possibly somewhat more recent than, those 

 which alone can have prevailed amongst the rocky islets of 

 the two Heads. The fragments from Llandudno are much 

 more worn than at Blackpool. Mr. Maw identifies the 

 boulder-clay as recurring to the south-east of the Head at 

 a height of 170 feet in the Gwydfyd valley, and says it 

 forms a terrace about the same height on the south side. 



* See Geol. Mag. ii. 298, 1865. 



