OF THE OUTER HEBRIDES. 823 



and there, also, I noted fragments of quartz-porphyries, none of 

 which could be identified as occurring in situ in Lewis. Scattered 

 promiscuously through the matrix are many broken shells. A large 

 number of these, owing to their fragmentary character, cannot be 

 determined. Such fragments as were recognizable I handed to my 

 friend Mr. Etheridge, who afterwards visited the sections with me, 

 but we had unfortunately very little time to bestow upon a further 

 search. A list of the fossils got by us is given by Mr. Etheridge in 

 the ' Geological Magazine ' for December 1876 ; they are only six 

 in number, viz. Truncatulina refulgens, Polystomella striato-punctata, 

 Cyprina islandica, Astarte sulcata, var. elliptica, A. compressa, var, 

 striata, Baxicava rugosa. A careful search would, I have no doubt, 

 add considerably to this list. 



The upper surface of this Boulder-clay is generally very uneven, 

 and is usually separated by a clear line of demarcation from the 

 beds that immediately overlie it. 



b. Inter glacial Beds. — These consist of dark blue and grey, and 

 sometimes brown laminated clay, silt, and mud, with sporadic stones, 

 the lamination being occasionally very indistinct or absent, overlain 

 by a series of stratified sand, gravel, and shingle, with here and 

 there large boulders. This double set, however, does not always 

 appear in one and the same section. In some places only the 

 laminated clay, in others only the sand and gravel beds are present ; 

 or, again, both may be replaced by a sandy silt, with intercalations 

 of sand, fine gravel, silt, and clay, and with stones not larger than 

 one's fist sparsely scattered throughout. The two sets of beds often 

 interosculate, but now and again the upper rests with a local un- 

 conformity upon the lower. But the general character of these 

 deposits will be better gathered from the accompanying sketch 

 sections and their explanations. Shells, sometimes whole, but 

 usually in detached valves, occur throughout ; they are mostly, how- 

 ever, mere fragments. The fossils we obtained are given by Mr. 

 Etheridge in the paper already referred to, but it may be useful to 

 mention them here. They are as follows : — 



Triloculina oblonga. 

 Quinqueloculina seminulum. 

 Dentalina communis. 

 Truncatulina lobatula. 

 Polystomella crispa. 

 Nonionina asterizans. 



depressula. 



Balanus balanoides. 

 Salicornaria, sp. 

 Pecten islandicus. 

 Leda pernula. 

 Cardium echinatum. 



edule. 



Cyprina islandica. 



Astarte sulcata. 



compressa, var. striata. 



depressa. 



Tellina balthica. 

 Mactra solida. 

 Mya truncata. 

 Dentalium entalis. 

 Turritella terebra. 

 Natica Alderi. 



Montacuti. 



Aporrbais pes-pelecani. 

 Buccinum undatum. 

 Trophon truncatus. 

 Fusus gracilis. 



c. Upper shelly Boulder-clay. — This is a reddish or brown sandy 

 clay, which, like the lower mass, is unstratified. In some" places it 

 is dark greyish blue and more clayey, and often becomes very tough. 



