﻿596 MR. E. B. BAILEY ON RECUMBENT FOLDS IN THE [NoV. I9IO, 



however, for some distance south of Salachan Glen, the Appin 

 Limestone is clearly in two distinct beds. Tn the Ballachulish Core 

 the Appin Phyllites reappear in five or six independent minor folds. 

 Though predominantly pelitic the group here, as in the Appin Core, 

 contains a large proportion of flaggy quartzite. 



The Ballachulish Granite reaches across from the Appin to the 

 Ballachulish Core, and for a quarter of a mile on either side of this 

 granite the more pelitic beds of the Appin Phyllites are converted 

 into spotted cordierite-hornfelses, while the portions containing 

 much flaggy quartzite are altered to a striped series well-nigh 

 indistinguishable from the Striped Series (4') intervening between 

 the Appin Quartzite and the Ballachulish Slates. 



The Appin Limestone was always suspected by Mr. Wilson to be 

 a dolomite, as in some outcrops it does not effervesce with acids. 

 Mr. Lightfoot has now shown that it varies in composition from a 

 sandy magnesiau limestone to true dolomite. In the field it gene- 

 rally weathers to a pale cream-colour with dark ribs, so that it has 

 sometimes been called the ' tiger rock.' The dark ribs are often 

 found to be pale in their interior when broken, but this is not always 

 the case. Both of the beds exposed on the Onich shore (Appin 

 Core) are of the 'tiger rock' type, and the beautiful exposures 

 in and near the ' Marble Quarry ' south of Ballachulish are also of 

 this type. Another variety occurs, which weathers in massive beds 

 with the faintest of blue-white tints. The bed occurring next to 

 the Appin Quartzite near the south-eastern margin of the Appin 

 Core, south of Salachan Glen, is of this type ; while the second bed 

 in this locality, lying farther south-east, is typical ' tiger rock.' 

 The same massive unstriped type is also well represented in the 

 Ballachulish Core, in proximity to the Appin Quartzite, on Sgorr 

 a' Choise. 



Where it approaches the Ballachulish Granite the Appin Lime- 

 stone loses its characteristic appearance, being generally converted 

 into a white crystalline marble or calc-silicate hornfels. In one 

 locality it even assumes a grey colour, thus mimicking the Balla- 

 chulish Limestone (6). This phenomenon is exhibited at the 

 southern end of the Sgorr a' Choise outcrop, in the neighbourhood 

 of a tongue from the Ballachulish Granite, and the grey colour is 

 found on examination to be due to finely disseminated crystals of 

 forsterite, as in the case of some of the ' dedolomitized ' Durness 

 Limestones described by Dr. Teall from the North-West Highlands. 



The repeated association of the Appin Limestone with the 

 Appin Quartzite, in many minor folds included within the two 

 major folds of Appin and Ballachulish, proves that the two zones 

 are in natural conjunction. In addition to this, the limestone 

 sometimes actually passes through a pebbly calcareous rock into 

 the Appin Quartzite, a phenomenon which may be observed near 

 Appin Station. 



(4) The Appin Quartzite is a massive, white, false-bedded, 

 pebbly quartzite, containing abundant pebbles of quartz and felspar. 



