The Loch na Cille Boulder Bed and its place in the Highland Succession

Abstract

I. Introduction and Literature The authors of the Geological Survey Memoir on Knapdale, Jura, and North Kintyre stated in 1911 that the real interest of the Tayvallich peninsula was far from being exhausted in their account, and that the geologist who visited its western shores would be well rewarded. This is undoubtedly true, for this region of the South-West Highlands, which includes all the promontories west of Loch Sween and south of Carsaig Bay and Loch a' Bhealaich, together with the adjacent islands, seems to afford some definite clues, hitherto apparently overlooked, which may prove to be important in the solution of the two great problems of Highland geology—the succession and the structure. To deal first with the succession: there may be said to be a general agreement amongst the workers in different parts of the area that the rocks seen belong to what has been termed the Loch Awe Group, which comprises the following members:— Quartzitic Series Limestone-Slaty-Schist Series (Tayvallich Limestones) Boulder Bed Tayvallich Volcanic Series There is, however, considerable difference of opinion upon the relationship of these beds to each other, and to the rock-groups of other regions outside this district. Some geologists, reading the whole in the light of what is seen in the Loch Awe country and some supposed evidence in the lavas, would place the Volcanic Series at the top and the Quartzitic Series at the bottom; this is the interpretation finally put forward in the Survey Memoir, where the supposed evidence of