BYRES ON GLACIER SCRATCHES. 



153 



and he thinks it probable, for this and other reasons, that the 

 deposit of the boulder clay was formed in a deep sea. 



2. On the Traces of the Action of Glaciers at Porth-Treiddyn, 

 in Carnarvonshire. By Robert W. Byres, Esq. 



Map of the supposed Path of the Glaciers from Snowdon. 



a. Moel Hebog. /. Tremadoc. 



b. Moel Wyn. g. Portmadoc. 



c. Bedd Gelert. h, h. Traeth Mawr. 



d. Pont Aber-glas-lyn. i. Traeth Bach. 



e. Brynteg. 



The following notice, bearing date the 16th of October, 1841, 

 appeared in the Visitors' book at the Goat-Hotel, Beddgellert : — 

 " Notice to Geologists. — At Pont-aber-glas-llyn, 100 yards below 

 the bridge, on the right bank of the river, and 20 feet above the 

 road, see a good example of the furrows, flutings, and striae on 

 rounded and polished surfaces of the rock, which Agassiz refers to 

 the action of glaciers. See many similar effects on the left, or 

 south-west, side of the pass of Llanberris. William Buckland." 



This notice led me to search for the same effects in other places 

 in the same neighbourhood, and I found similar traces on many of 

 the rocks between Aber-glas-llyn bridge and Tremadoc. In 

 February last curiosity led me into the Flag-quarry, which lies 

 about 300 yards from the mail-coach road, at Porth-Treiddyn ; and 

 for the purpose of examining the joints and split of the rock, I 



