loo The Irish Naturalist. [ April, 



time, the results of brecciation of bedded rocks (" crush-conglomerates ") 

 are well recognised among the shales and limestones at the south end 

 of the section. The authors reproduce Mr. H. Preston's fine photographs 

 of the features due to this brecciation, taken during the visit of the 

 Geologists' Association to Dublin in 1893. 



The limestone of the Chair of Kildare is shown to be palaeontologically 

 identical with that known as the Keisley I^imestone in the English Lake 

 District (i., p. 594), a local variety of the Coniston Limestone. The Bala 

 age of these beds is thus unassailed. The remarkable lithological 

 difference of the beds at Dunmurr}- and Grange Clare Hills, when 

 compared with those of the Chair, leads the authors to suggest that they 

 are truly Silurian. They are, unfortunately, practically devoid of fossil 

 (i., p. 595). 



In the second paper, we have a new detailed section and map of the 

 complex little promontory of Portraine, which will assist all future 

 visitors The real additions to our knowledge are in the lists of fossils 

 collected (ii., pp. 535-539^- Mr. Cowper Reed places the compact 

 limestone of Portraine with that of the Chair of Kildare, as of L^pper 

 Bala age, and the coral-beds below it as Middle Bala. The authors 

 regard the unfossiliferous " grits and slates," which overlie the compact 

 limestone and stretch southward along the shore, as identical with those 

 near Balbriggan, which are of Birkhill (Llandover}') age (ii., p. 531). Is 

 so, we have true Silurian beds in close proximity to Dublin. 



The difficulty of arriving at or leaving Lambay Island in moderately 

 windy weather renders it hardly visited, except by occasional pleasure- 

 steamers in the summer. Prof Sollas established a camp there some 

 years back ; and it is to be hoped that the paper of Messrs. Gardiner 

 and Reynolds leaves him still some new points to publish from the 

 observations made by him at that time. The map (iii., pi. ix. ), now put 

 before us adds very greatly to our information. The palaeontological 

 evidence is scanty ; but the slates and limestones of the island seem to 

 correspond with those across the water at Portraine. An interesting 

 conglon:erate is shown to be contemporaneous with these, and consists 

 largely of blocks of limestone, worn from the coral-banks of Ordovician 

 days. 



The well-known "Lambay porphyry" occupies, after all, only a few 

 .small areas in the volcanic mass of the island. On the east, it occurs 

 apparently as a lava-flow (iii., p. 146), while at other points it comes up 

 in dykes or sills. No great neck is found in the island, such as previous 

 writers had predicted ; and the centre of eruption for the andesites, both 

 of Lambay and Portraine, may lie out in the Channel to the east. 



Dwellers in Dublin, particularly, will feel grateful to Messrs. Gardiner 

 and Reynolds for these careful essays ; and further visits from Cambridge 

 workers will be welcomed, in a country where those engaged in geological 

 research are still unhappily too few. 



Grenvii^i^k a. J. Cole. 



