"CHUI"@en . . . "Abrupt change to the more uniform garnetiferous semipelite rocks of the Beinn Dorain Semipelite Formation."@en . "stable"@en . "Quartzite with subsidiary semipelite. Stratified bedrock. Occurs onshore. Deposited during the Cryogenian Period (Precambrian) (720-635 Ma BP)."@en . . "720.0"^^ . "Allt A'Chuirn Quartzite Member"@en . . . . . "635.0"^^ . . "10 to 30cm-thick layers of quartzite, commonly ribbed in appearance; muscovitic semipelite typically accounts for less than 10% of the lithology, The base is gradational with the underlying part of the Beinn an Dothaidh Formation."@en . "Allt A'Chuirn Quartzite Member"@en . "c 200m thickness is observed in the Allt a'Chuirn section but is greatly thickened by the effects of folding, estimated stratigraphical thickness is in the order of 30 to 50m."@en . "The base is gradational with the underlying part of the Beinn an Dothaidh Formation, with an upwards change to quartzite as the dominant lithology."@en .