1865.] BRTCE— AEEAN DEIFT-BEDS. 207 



showing that it was formed partly out of the Boulder-clay, and on 

 the spot, over the bottom where the shells were living. The only 

 shells found in this bed which are absolutely Arctic are Pecten 

 Islandicus and Astarte horealis, but these are sufficient to show 

 the Arctic character of the bed. The greater number of the 

 shells are in a broken state or in single valves, yet the fragments 

 are generally so large that the species can be determined. The fol- 

 lowing occur either fragmentary or in single perfect valves, in 

 addition to the two species already given: — Oyprina Islandica, 

 Modiola modiolus, Astarte compressa, A. elliptica. The shell-bed 

 is seen over the Boulder-clay from the southern end of the section 

 across its entire front, ascending northwards with the slope of the 

 bed below : the same species are found in it throughout. The part 

 of it most accessible for working is on a slip towards the southern 

 part of the section. The shells are found in no other part of the 

 series except when washed out and carried to lower levels. 



Over the shell-bed there is a series of other beds presenting 

 considerable diversity of character among themselves, but, when 

 covered in front, with their facing looking very Hke the Boulder- 

 clay. When, however, the false face is removed they are seen to be 

 very different ; they are more sandy and less compact, more loose 

 and easily broken. The imbedded stones are usually angular ; stria- 

 tion or polishing is rarely seen, or if polished there is a far less per- 

 fect finish than on the stones of the Boulder-clay, as if they had 

 been exposed, after the polish was put on, to a continual wearing- 

 action. They are, indeed, very like a river-deposit, and have much 

 resemblance to the heaps of detritus left by floods on the banks 

 of the stream below. The series may be designated the " Upper 

 Drifts." The following section presents in descending order the 

 whole series of beds at this place : — 

 7. Surface soil. 



6. Sand and stones, usually reddish ; thickness variable. 

 5. Compact bed of stones, 5 or 6 feet thick, forming a 



marked line on the cliff; difficult to reach here. 

 4. Sand, clay, and stones ; thickness variable. 

 3. Dark sandy bed, of open texture, 4 or 5 feet ; apparently 



local. 

 2. Clay-bed with shells, 7 to 10 feet. 

 1. Boulder-clay, 12 to 20 feet thick. 

 On the principal stream, the Torlin-water, opposite to Kilmorie 

 Church, and on the west side of a sweep in the bank, there is a re- 

 markable section. The true Boulder-clay (that is, the lowest bed) 

 is everywhere subject to great and sudden undulations ; the upper 

 surface seems as if thrown up in waves and depressed into deep 

 hollows ; in some places it becomes rudimentary or thins out 

 wholly, in others, not far removed, it attains great thickness. At 

 the place above indicated, the true Boulder-clay or lower Till is ab- 

 sent, and the shell-bed rests on the natural rock and thins out 

 southward ; in the opposite direction there are indications of the 

 Boiilder-clay coming on under the shell-bed as the ground rises 



VOL. XXI. PART I. Q 



