282 mr. e. e. bailey on the [June 1 9 13, 



for he had been transferred to the English staff in 1897, and 

 most of his time -was thenceforward occupied in Cornwall. In 

 1901 Dr. B. N. Peach came into the district, and, with the late* 

 Mr. J. S. Grant Wilson and Mr. H. B. Maufe, carried the survey 

 down the two sides of Loch Craignish ; the Craignish peninsula 

 itself fell mainly to Mr. Maufe. Later all three mapped small 

 disconnected areas iu the more southern part of the district ; 

 Dr. Peach undertook the examination of the Tayvallich peninsula 

 himself, there making a most important discovery to which I 

 shall return presently. In 1904 Dr. Peach left the West High- 

 lands for Ross-shire, and Mr. dough returned once more to 

 Argyllshire. Mr. Wilson died in 1908, and Mr. Maufe left for 

 Rhodesia in 1910. By this time mapping in the district had 

 already been brought to a close (1906), but the southernmost of 

 the 1-inch maps (Sheet 28), with its explanatory memoir, did not 

 appear till 1911. My own connexion with the district dates from 

 1902, when I started work south of Loch Crinan. The conditions 

 were very advantageous, as Dr. Peach was making geological 

 history rapidly in those days, and always kept me in touch with 

 his latest results. Por a couple of seasons Mr. G. W. Grabham 

 was working on the two sides of Loch Caoilisport, along with 

 Mr. Clough; but Africa claimed him too, and in 1906 he went to 

 the Sudan. In the same year Mr. W. B. Wright also undertook 

 the mapping of a small area east of Loch Caoilisport, thus helping 

 to complete the survey. 



Naturally, as a result of so much co-operation, a great advance in 

 our knowledge of the district was achieved. It is the purpose of 

 the present paper to develop two somewhat important points, 

 concerning which it seems to me that conclusions previously arrived 

 at and published by Mr. Hill call for modification : — 



1. Dr. Peach has shown that the epidiorites of the region include many 

 volcanic rocks, whereas Mr. Hiil regards them all, in the district which he 

 has mapped, as intrusive. 



2. I have myself introduced a considerable alteration in the reading of 

 the stratigraphy of the Loch Awe Group. 



These two points have a close connexion, for, as a matter of 

 fact, Dr. Peach's discovery of a recognizable volcanic zone afforded 

 a valuable additional clue in the disentanglement of the strati- 

 graphical problem. It is convenient, however, to consider them 

 apart, indicating very briefly the progress of research in each case. 



II. The Volcanic Rocks. 



In 1903 Dr. Peach discovered unmistakable pillow - lavas 

 (PI. XXXI) exposed on the coast south of Tayvallich, in asso- 

 ciation with black slates, limestones, and fragmental rocks like 

 tuffs and agglomerates [13, p. 59]. The discovery came rather 

 late in the day, for by this time all the district north of Tay- 

 vallich had already been mapped. Still, there were several records 



