GEOLOGICAL SOCIETY OF LONDON. 



51 



obtained from so limited a space as the Isle of Slieppy ex- 

 ceeds that of the species of Chelone now existing, and that 

 of these only two (C. my das ^ C. caretta) are known to fre- 

 quent the same locality, that the ancient ocean of the Eocene 

 epoch was less sparingly inhabited by turtles, and that they 

 presented a greater variety of specific modifications than are 

 known in the seas of warmer latitudes of the present day. 



December I5th 1841. — R. J. Murchison, Esq., Presi- 

 dent, in the chair. A copy of the great geological map of 

 France, by M. Dufrenoy and M. Elie de Beaumont, accom- 

 panied by a letter from those gentlemen, and the 1 st vol of 

 the Description of the Chart, was presented to the Society, 

 in their name, by the President. 



1 . A paper was read, entitled : " On dihwio-glacial phe- 

 nomena in S7iowdonia and the adjacent parts of North-Wales ^ 

 By Dr. Buckland. 



Dr. Buckland and Mr. Sopwith state that many evidences of the ac- 

 tion of ice may be observed upon the sides and bottoms of all the princi- 

 pal valleys in Snowdonia. In 1824, Mr. T. Underwood made drawings 

 of polished, striated, and furrowed surfaces in the vales of Conway and 

 Llanberis ; Mr. Joshua Trimmer also pointed out, in 1836, similar sur- 

 faces on slate rocks in the Nantle valley, on the West of Snowdon. 

 Subsequently Mr. J. E. Bowman published an account of striated sur- 

 faces of slate rocks near Llangollen and Pen Tre Voelas, although he 

 states that he was unable to discover in North- Wales any evidences of 

 lateral moraines. 



Seven principal valleys, taking as many different direc- 

 tions have their origin in that highest district of Caernar- 

 vonshire, which forms the district of Snowdonia; viz. the 

 valleys of the Conway, Lugwy, Ogwyn, Sciant, Gwyrfani, 

 Llyfni and Gwynant, and nearly all of these have their sides 

 and bottoms rounded and polished, and scored with strice 

 parallel to the mean direction in which either a glacier or 

 overwhelming current of water descending each valley would 

 assume under the existing contour of their respective siirfa« 



E 2 



