Professor R. M. Shackleton thought that the Deer Park high grade rocks were more likely to be Moine or Lower Dalradian than pre-Moine basement. At least in lower Dalradian times, there was no Basement geanticline between Connemara and the main Dalradian areas; the Islay succession in Connemara is remarkably similar to that in Mayo, Donegal and Scotland. The metadolerites with relict ophitic textures, intruded in the Deer Park assemblage after the first deformation, can be matched in the Dalradian. If they were pre-Moinian, it would be necessary to suppose that the Deer Park assemblage represents an uplifted area which escaped the effects of the high grade metamorphisms which affected Connemara only a short distance to the south. The speaker thought that metamorphism might well have been affecting the deeper Dalradian rocks while the upper Dalradian was still being deposited.

Amongst many points of interest brought forward by Dr Phillips the speaker noted the record of oolitic limestones, clearly of shallow-water origin, closely associated with graphitic pelites, jaspers and turbidites which were often nowadays taken to be abyssal oceanic deposits.

Mr R. Anderton: I am very interested to hear Dr Phillips's evidence for Dalradian Syndepositional faulting and the existence of an uplifted area to the south of Glare Island forming a source of Upper Dalradian sediments. My own work on the sedimentation of part of the Middle Dalradian in Argyll strongly implies the existence of several syndepositional faults with vertical displacement of the order of kilometres which strongly influence, if

This content is PDF only. Please click on the PDF icon to access.

First Page Preview

First page PDF preview
You do not currently have access to this article.