1841 GEOLOGICAL WORK IN SOUTH WALES 51 



published even in abstract. It is entitled ' Report on 

 the work entrusted to A. C. Ramsay in North Pem- 

 brokeshire, and part of Cardiganshire and Caermar- 

 thenshire.' The MS., which is in his handwriting, 

 remains in the archives of the Geological Survey. In 

 this document he gave special prominence to the 

 igneous rocks, which he separated into intrusive and 

 contemporaneous, showing that the latter cover by far 

 the greater area. Among the rocks of St. David's 

 he clearly recognised the presence of volcanic ash, and 

 saw in these rocks the records of prolonged volcanic 

 activity. Other geologists, notably Sedgwick, Mur- 

 chison, and De la Beche, had described the proofs of 

 contemporaneous volcanic eruptions among stratified 

 formations of old geological date. But Ramsay was 

 the first to trace out in detail the structure of a 

 volcanic series of such high antiquity, and to separate 

 from each other the outflowing lavas, the ejected 

 ashes, and the deep-seated intrusive sills. When we 

 remember, too, that this was practically his first piece 

 of detailed mapping, we cannot fail to acknowledge 

 the earnest which was thus given of the future 

 geological accomplishment of the surveyor. 



It fell to Murchison's lot as President of the 

 Geological Society in 1843 to gi ye some account of 

 the recent proceedings of the Geological Survey in his 

 address at the Anniversary of the Society in February. 

 He referred to the increasing evidence brought for- 

 ward by the officers of the Survey that the interior of 

 South Wales, which had been vaguely referred by him 

 to Sedgwick's ' Cambrian ' system, consisted largely 

 of Lower Silurian rocks. He spoke of the Survey's 

 * results, obtained among strata so obscured by change, 

 as among the very highest triumphs of geological 



