I909- 



THE LOWER PA^L.^OZOIC ROCKS AROUND 

 KILLARY HARBOUR.' 



BY R. G. CARRUTHKRvS AND H. B. MUFF. 



The Lower Palaeozoic rocks of the Killary Harbour region, 

 whicli comprises some of the most mountainous countr}* in 

 the West of Ireland, are of interest for several reasons. Far 

 removed from the typical areas of Shropshire and North 

 Wales, these rocks present the most westerly development of 

 the Ordovician and Silurian S3\stems to be found in Europe. 

 They lie widely apart from the rocks of similar age to be found 

 in the north and east of Ireland, from which they differ greath' 

 in lithological character. Moreover, they furnish definite' 

 evidence of the relation of the Lower Palccozoic rocks to the 

 Crystalline Schists, information which is difficult to obtain in 

 any other portion of the British Isles. 



- Although the geological structure is simple, and is clearh' 

 seen in such a hilly tract, the scarcity of fossils only 

 permitted former observers to lay down various broad 

 divisions of the strata, and a true comparison of the 

 fauna with those of other areas was hardly practicable. 

 In the maps and memoirs of the Geological Survey, pub- 

 lished between 1874 and 187S, the main divisions of the 

 strata and their structural relations were laid down. 

 These divisions were distinct lithologically, and on palaeonto- 

 logical evidence, were assigned to various members of the 

 Silurian and Ordovician Systems (grouped at that time as 

 Upper Silurian and Lower Silurian respectively). 

 They were, in descending order : — 



(. Salrock Slates (Ludlow) 

 UDDer Silurian \ ^^eelrea Beds (including Leenane Grits) 

 \ , I (Wenlock) 



. Owen duff Series (Llandovery) 



Lower Silurian. Doolough Series (including Rossroe Grits) 



(Bala and ? Llandeilo). 



■I- Read before the British Associatioii, Sectioii C (Geology), DubHu, 

 September, 1908. 



