Professor Charles Lapworth, LL.D., F.R.S. 291 



with any success. It is well known that previous to Lapworth's 

 researches the Silurian rocks of the Southern Uplands had been 

 considered to be a normal ascending sequence of greywaokes, of 

 enormous thickness, interrupted by occasional thin seams of black, 

 graptolitic shale. As the graptolite fauna of each shale mass was 

 broadly the same as that of every other mass, it was naturally 

 considered that the Upland series had been rapidly deposited, 

 without any important organic change taking place from base to 

 summit ; and that, consequently, graptolites were of no use for zone 

 work. Important negative conclusions in the matter of evolution 

 followed as a corollary. 



One of the first things that made Lapworth suspect that things 

 were not as they seemed was, that graptolites of highly divergent 

 types, though found near together, were never met with on the same 

 slab of rock ; and this was followed by the discovery that there 

 was always a difference, sometimes generic and always specific, 

 in the faunas of contiguous and successive bands in each shale mass. 



When he had discovered that on proceeding downwards from the 

 greywacke of Dobb's Linn a definite sequence of graptolites was 

 met with down to a certain point, he hit upon the important fact 

 that a corresponding and practically identical sequence was met with 

 also, but in inverted order, in descending beyond this point until 

 greywackes were again reached. It is said that, on first suspecting 

 this, Lapworth rushed into the field and, reaching Dobb's Linn in the 

 twilight, he rapidly collected one series of graptolites in descending 

 to the critical point which he placed in his right-hand pockets, and 

 another in descending below it which he put in the left-hand pockets ; 

 he then carried both series off to his lodgings to compare in the 

 lamplight. The comparison verified his hypothesis, and he now 

 held the proof that in this locality, at all events, half the rock 

 succession was inverted. Indeed, he had got hold of the right end 

 of the clue which subsequently enabled him to unravel the com- 

 plicated stratigraphy of the region. To this task he now devoted 

 his spare time for seven or eight years, nor did he stop until he had 

 followed the divisions of the Moffat Shale from sea to sea, mapping 

 the critical areas in great detail, sometimes on the 6 inch scale, but 

 in most instances surveying and constructing his own larger scale 

 maps of the special localities, in which he could insert the zones 

 as they occurred in the field. At the same time he acquired the 

 large collection of graptolites necessary to verify his conclusions and 

 complete his knowledge of the fauna. 



Although probably himself satisfied that the hypothesis of 

 a chronological sequence of graptolite zones, which worked so 

 well in elucidating the complicated structure of the Mofilit region, 

 must be in the main a correct one for the Uplands generally, 

 Lapworth proceeded to apply the severest test that he could think 

 of to his conclusions. For that purpose he selected next the 

 Girvan area, where the rocks have a different facies and graptolite- 

 bearing seams are rare or subordinate, but where it was already 

 known that there is a vast array of other Silurian fossils and very 



