Issues

Dr M. Ltherland writes: Whilst Lambert et al. noted that anomalous Rb and Y values from the ‘Leven Schists’ of Glen Creran may ‘imply that schists from another Dalradian horizon have been sampled’ (p.74), their fig. 1 shows only Appin Group under-lying the Loch Creran area, in contrast with previous workers, who also included Argyll Group (Iltay) rocks (Bailey 1922; Voll 1964; Rast & Litherland 1970; Litherland 1980).

The stratigraphic details of the Appin and Argyll Groups at Loch Creran are given in Litherland (1980). The Leven Schists sensu stricto, i.e. that formation which stratigraphically underlies the Ballachulish Limestone,are confined to the floor of Glen Creran and the NE-trending Airds Hill belt, where the unit exhibits facies changes.

Clearly, Lambert et al. sampled rocks other than Leven Schists in the Glen Creran area and, although no grid positions are given, if these rocks were the ‘coarsely-banded schists with alternating quartzose and black pelitic bands’ (p. 72), then they sampled Argyll Group or horizons above the Lismore Limestone. The east ward change (p. 72) from the ‘green laminated facies’ of the Leven Schists to the above rocks was probably noted at Glen Salachan, where the Bendeloch Slide divides the Leven Schists from the Argyll Group (Litherland 1980, 1982). However, doubts regarding my reinterpretation are excusable in this particular section, since similar striped and graded silt stones are found in close proximity on either side of the slide. That one of these striped siltstones belongs to the Leven Schists and the other

Report of a meeting of the Metamorphic Studies Group held at Burlington House, 3 March 1982. The meeting was organized by Dr M . Brown.

The fourthmeeting of the Metamorphic Studies Group and the Group's first Annual General Meeting were held at Burlington House on 3 March 1982. Approximately 50 members attended the meeting and 11 papers covering a wide range of topics on the theme ‘Metamorphic studies: research in progress’ werepre-sented; 5 of the apers involved current or recent research students and it remains the policy of the Group to encourage research students to contribute to its meetings.

The morning session,chaired by Professor Bernard Leake, was opened by Gibbons who presented an interesting account of his work with Mann on the tectono-metamorphic development of the Penmynydd Zone rocks of Anglesey and the Lleyn Peninsula, N Wales. Thiszone is re-interpreted by Gibbons & Mann as being the surface expression of 2 major shear zones,the Central Unit of Anglesey and the Aethwy-Llýn Unit of SE Anglesey and the Lleyn Peninsula, and representing movement of sialic basement into the overlying, unmetamorphosed Gwna Group rocks. The minerals developed during the metamorphic maximum (biotite, garnet and stilpnomelane in the Central Unit and lawsonite in parts of the Aethwy-Llgn Unit, which is generally characterized by blueschist facies metamorphism overprinting an earlier greenschist facies metamorphism) post-date the main tectono- metamorphic fabric in the rocks but pre-date late brittle and ductile shearing. Gibbons & Mann presented 2 alternative models for the development of the blue-schists: either achieving