i8 4 i GEOLOGICAL WORK IN SOUTH WALES 53 



the time, was afterwards adopted as the boundary 

 between the Cambrian and Silurian systems. It was 

 in those days the belief of the great body of geologists 

 that the older rocks of South Wales belonged to Sedg- 

 wick s Cambrian formations, and as such they were 

 coloured on the large map accompanying Murchison s 

 Silurian System, published in 1839. A few fossils had 

 indeed been found in them which were of Lower 

 Silurian species, but the evidence supplied by these 

 fossils does not seem to have been considered strong 

 enough to change the general current of opinion. 

 When in 1841 the Survey began to map the region 

 about Haverfordwest, neither De la Beche nor his 

 officers could find any base to the series which, by 

 common consent, was acknowledged to be Lower 

 Silurian. And when in that and the following year 

 Ramsay and others obtained Lower Silurian fossils at 

 various points across the whole breadth of South 

 Wales, they could come to no other conclusion than 

 that this wide region consisted of Lower Silurian 

 rocks repeated in endless undulations. 



Much more detailed work would now be possible 

 in South Wales than is shown upon the maps of the 

 Geological Survey. But those who may in future 

 carry out this re-survey will doubtless be the first to 

 admit the value of the work of the pioneers who pro 

 duced the first geological map of that difficult tract of 

 country. Ramsay himself was well aware of the 

 imperfection of the early work in South Wales, as will 

 be apparent in later pages of this volume. 



Of the actual daily life of these first years 

 of his Survey experience in Wales little record 

 seems to have been preserved. He used to tell in 

 later life how, when stationed at St. David s during 



