258 The Founders of Geology LECT. 



and found there a wider field of action. After a time 

 Murehison also became a fellow of the Society, and he and 

 Sedgwick soon formed a close intimacy. This friendship 

 proved to be of signal service to the cause of geological 

 progress. The two associates were drawn towards the 

 same departments of investigation. They began their 

 co-operation in the year 1827 by a journey through the 

 west and north of Scotland, and from that time onward for 

 many years they were constantly working together in 

 Britain and on the Continent of Europe. 



It would be interesting, but out of place here, to linger 

 over the various conjoint labours of these two great 

 pioneers in Palaeozoic geology. We are only concerned 

 with what they did, separately and in conjunction, towards 

 the enlargement of the geological record and the definite 

 establishment of the Palaeozoic systems. Sedgwick began 

 his work among the older fossiliferous formations by 

 attacking the rugged and complicated region of Cumber- 

 land and Westmoreland, commonly known as the Lake 

 District, and in a series of papers communicated to the 

 Geological Society he worked out the general structure of 

 that difficult tract of country. Though fossils had been 

 found in the rocks, he did not at first make use of 

 them for purposes of stratigraphical classification. He 

 ascertained the succession of the great groups of strata by 

 noting their lithological characters. One of the most 

 remarkable features of his investigation was the recogni- 

 tion of volcanic rocks intercalated among the ancient 

 marine sediments of the Lake District. These rocks, since 

 so fully worked out, and now known as the " Borrowdale 

 Volcanic Series," of Lower Silurian age, were first assigned 



