Glenelg - a brief visit to Moine-Lewisian geology

[@micklumb645]

Excellent, as always, Rob...your deep affection for this area and it's geology really shows through! I've learned a lot.

[@Martytalius]

Great video, Rob! I'm curious at how the overturning of the contact between the Moine meta sediments and the Lewisian gneisses was determined at the outcrop you were at in the video. Was it the asymmetry of parasitic folding, inverted grading from metamorphic minerals, bedding-cleavage relationships? I imagine it would be fairly hard at that contact with how strongly strained the rocks looked

[@robbutler2095]

Hi - the way-up around the inliers was established by Ramsay who identified cross-bedding in the psammites. For the pelites - well these can be found rimming some inliers and so placed in a local succession. But you're correct - at Sandaig, those pelites are pretty far-gone... Many of the "parasitic" folds plunge down the regional stretching lineation so hard/impossible to establish vergence....

[@nadiasourez8560]

P light ? What does it mean please.thank you

[@robbutler2095]

It's pelite - a metasediment derived from fine-grained siliciclastic sedimentary rocks - claystones, mudstones (±fine sandstones). As they have a wide chemical composition (compared with simple sandstones), they can form a wide range of minerals during metamorphism.