i8 4 7 EDWARD FORBES 109 



various members of the Silurian series. From Dolau- 

 cothi the two geologists made their way by Llangadoc 

 and Llandovery to Builth, where they saw the Car- 

 neddau, with its unconformability, then by Pen y bont, 

 Kington, Ludlow, Church Stretton, Bishop's Castle, 

 and Chirbury to Welshpool. In this tour Ramsay, 

 still unable to use his foot, was compelled to ride, 

 while Forbes walked at his side. Being familiar with 

 the ground, however, he was able to point out all the 

 salient features of geological structure. * I explained,' 

 he says in his diary, ' and Forbes believed in all the 

 geology.' As Forbes had not had any opportunity of 

 making himself familiar with the older Palaeozoic rocks, 

 it was of great benefit to him, and of much ultimate 

 advantage to the Survey, that he should learn his 

 lesson in such a typical region, and under the guidance 

 of the best stratigrapher on the staff. 



There was not, however, always perfect agreement 

 between the two travellers. So long as only the facts 

 of geological structure were concerned, Forbes was 

 quite content to take them from Ramsay, but when 

 it came to the interpretation of these facts, and to 

 theoretical deductions from them, he claimed to use 

 his own judgment. Notwithstanding the experience 

 gained in mapping the Cader Idris country, and in 

 traversing the Arenig chain, Ramsay still retained, 

 and indeed maintained to the last, his belief in the 

 conversion of stratified rocks, through the contact 

 metamorphism induced by intrusive masses of igneous 

 material, into substances that could not be distin- 

 guished from true igneous rocks. He supposed that 

 the sedimentary strata had been actually melted, and 

 that from this molten condition a gradation could be 

 traced, on the one hand, into the ordinary character of 



