518 Notices of Memoirs — J. Wright — Boulder-Clay. 



fauna, from which much of the history of the intervening period 

 may be gleaned. A typical section at Belfast shows the following 

 sequence : — 



ft. in. . 



Surface clays ... , 6 6 



Yellow sand 2 



^>"-'»y{?rr ;;; ::: :;: ::: ::: \ S 



Grey sand 2 



Peat 1 6 



Grey sand 2 



Eedsand 4 



Boulder-clay (base not reached) 15 



45 



The peat bed, which at Belfast is twenty feet below low-water level, 

 reappears between tides at various other places in the district. It 

 represents an old land-surface, and its fossils include the 'Irish 

 Elk.' The blue clay is the most important bed of the series. Two 

 divisions can be clearly distinguished in it, the lower clay being 

 littoral, and characterised by such shells as Scrobicidaria piperata, 

 the upper yielding an abundant fauna pertaining to five to ten fathoms 

 of water. Tliracia convexa is a characteristic fossil. In both clays 

 some of the bivalves occur in beds, each shell in its natural position, 

 and many of the species attain remarkably large proportions. In 

 places the Scrohicularia clay is overlaid by raised beaches. Thus, 

 at Larne, twenty feet of stratified gravels, containing marine shells 

 and neolithic implements throughout, replace the Tliracia clay, and 

 serve to date it. The fauna of the Thracia clay has a distinctly 

 southern aspect when compared with the present fauna. 



As regards oscillations of level, the peat proves a level higher 

 than the present in certain places by at least thirty feet. Subsidence, 

 irregular both as regards rate and area affected, superseded to the 

 extent of fifty to eighty feet ; the final elevation, which brought 

 about the existing state of things, amounted to thirty or forty feet. 



As regards climate, the northern fauna of the Glacial period 

 appears to have passed away by the time the peat was formed. 

 Southern species immigrated till the molluscan fauna acquired a 

 distinctly southern character in the upper blue clay ; then the seas 

 became again colder, and the present local molluscan fauna has 

 a distinctly northern aspect. 



V. — On the Marine Fauna of the Bouldee-Clay. 

 By Joseph Wright, F.G.S.^ 



rilHE author has examined microscopically 112 samples of boulder- 

 JL clay from various places in the British Isles and in Canada : 

 47 of these were from Ireland, 27 from England and Wales, 22 from 

 Scotland, 1 from the Isle of Man, and 14 from Canada. In 71 of 

 the British and in 9 of the Canadian samples foraminifera were 

 found ; the specimens of the clays had been taken from various 



^ Abstract of a paper read before the British Association, Belfast, September, 1902, 

 in Section C (Geology) . 



