RECENT ADDITIONS TO ANCIENT SEDIMENTS. 365 



recent years in the correlation of deposits of various areas, — 

 a task which is still viewed with some suspicion by certain 

 geologists of the old school ; it is for all that a very necessary 

 task, for, unless it is done, our science will remain in an im- 

 perfect stage of advancement, for how are we to write the 

 history of the earth, unless we can refer the various events 

 which occurred to their proper periods ? The methods of 

 work have been commented upon in the foregoing pages, but 

 the work itself has only begun, and a wide field for fresh 

 research in this direction lies open to the stratigraphical 

 student. 



RECENT APPLICATIONS OF STRATIGRAPHICAL 



KNOWLEDGE. 



Already a rich harvest has been reaped as a consequence 

 of the zonal method of stratigraphical work. Every branch of 

 geological science, physical and biological, has profited, but 

 it must suffice here to take a few examples of the benefits 

 which have accrued to different branches, and we will con- 

 sider the effects of recent stratigraphical work upon our 

 knowledge of deposition of sediment, earth-movement, rock- 

 metamorphism, and organic evolution. 



The detailed work of Lapworth, in the Moffat area, was 

 followed by an examination of the equivalent rocks in Ayr- 

 shire (28), and accordingly a complete comparison could be 

 made between the thin graptolite-bearing deposits of Dum- 

 friesshire and the much thicker deposits crowded with 

 remains of various organisms, which are developed around 

 Girvan. The remarkable changes in the lithological and 

 palseontological characters of the rocks within this short dis- 

 tance throw much light upon the condition of deposit during 

 lower Palaeozoic times, and as the result of his Moffat and 

 Girvan work, and an extension of it into adjoining regions, 

 Lapworth gave us that remarkable paper on the Ballantrae 

 rocks (29), in which the local variations in the characters of 

 the deposits are traced from the Pentland Hills to Kirkcud- 

 bright. A further important result of the work in the 



