Vol. 69.] LOCH AWE SYNCLINE (ARGYLLSHIRE). 291 



had as yet been published. This want was rectified when, as already 

 mentioned, Sheet 37 and its accompanying Memoir appeared in 

 1905 [14]. My visit to the district in the following spring led me 

 to replace the previous classification of the Loch Awe Group by the 

 following : — 



Loch Avich Green Slates and Grits (volcanic rocks in the lower part), 

 Tayvallich Black Slates and Limestones (volcanic rocks throughout), 

 Crinan Quartzites and Grits, 

 Shira Limestone. 



Of these zones, the Shira Limestone may be regarded as in part 

 belonging to the underlying Ardrishaig Phyllite Group. 



In the 1906 traverse, I found that this new classification held 

 good in the central and eastern parts of the Loch Awe district and 

 also in the Tayvallich peninsula, where T was fortunate enough to 

 obtain clear evidence that the Tayvallich Slates and Limestones 

 structurally overlie the main mass of quartzite. At the same time, 

 I was still ready to believe that Dr. Peach's interpretation would 

 •hold without serious modification in the district south and west of 

 Loch Avich, where he had originally developed it in conjunction with 

 Mr. Maufe and Mr. Grant Wilson. I thought it likely, therefore, 

 that the Craignish Phyllites would prove to belong to the Loch Avich 

 division of the Loch Awe Group, and not to the Ardrishaig Group 

 as heretofore supposed. However, this view has been perforce 

 abandoned in the light of farther research. On the publication of 

 Sheet 45 with its explanatory memoir, in 1908, 1 immediately visited 

 the northern part of the district, and in the same year I had the 

 great advantage of a joint traverse with Mr. Maufe, in official time, 

 through the country on both sides of Loch Craignish. The result 

 of this more recent work was to vindicate Mr. Hill's correlation of 

 the Craignish and Ardrishaig Phyllites — a correlation all along 

 accepted by l)r. Peach ; and, at the same time, to convince me that 

 the north-western portion of the Loch Awe outcrop was susceptible 

 of reinterpretation in such manner as to bring it into line with 

 the rest of the district. About this time Dr. Peach realized 

 the cumulative force of the evidence acquired, and so the two of 

 us were able to co-operate in the description of the Tayvallich 

 peninsula given in the memoir dealing with Sheet 28, which 

 appeared in 1911. Since then I have not revisited the ground, 

 •except for a few days in 1912, when I returned to Loch Awe, and, 

 among other things, examined the northern termination of the 

 outcrop of the Loch Avich Slates and Grits. 



Before giving the evidence for the new interpretation, I think it 

 better to state quite clearly that it has not gained acceptance from 

 Mr. Hill. We paid an official visit together to the Tayvallich 

 peninsula in the spring of 1909, but Mr. Hill did not find the 

 evidence presented to him sufficiently convincing to shake his 

 •old-established faith. His views upon the matter are set forth in 

 the Survey Memoir [18, p. 61], where he indicates that his inter- 

 pretation of the Loch Awe sequence has been influenced by the fact 



