Editing Old Red Sandstone (section)

=== Argyll ===
There are a scatter of exposures of the Old Red Sandstone around [[Oban]] and the [[Kerrera|Isle of Kerrera]] on the [[West Highland]] coast, this unit is sometimes referred to as the Kerrera Sandstone Formation. The unit is up to 128m thick in its type area and consists of green and red sandstones and conglomerates, typically containing large ({{convert|10|-|30|cm|in|0|abbr=on|disp=or}} across) elliptical well rounded clasts, accompanied by siltstones, mudstones and limestones.<ref>{{cite web|url=https://www.bgs.ac.uk/lexicon/lexicon.cfm?pub=KESA|title=Kerrera Sandstone Formation|website=BGS Lexicon of Named Rock Units|publisher=British Geological Survey|access-date=31 October 2018}}</ref> On Kerrera a conglomerate of [[andesite]] boulders rests unconformably on [[Dalradian]] black, [[Pyrite|pyritic]] [[slate]]s ([[Easdale]] Slate) of the [[Argyll_Group#Easdale_Subgroup|Easdale Subgroup]]. At Oban there is merely an erosional contact incorporating debris of the slate in a basal conglomerate. The ORS deposits around Oban are considered latest Silurian ([[Pridoli Epoch|Pridoli]]) to earliest Devonian in age. They are interpreted as [[alluvial fan]]s which filled a depositional basin from the east and northeast.<ref>British Geological Survey 1:50,000 scale geological map sheet 45W (Scotland) ''Connel'' 1991</ref>  Small [[inliers and outliers (geology)|outliers]] occur near [[Taynuilt]] and either side of [[Loch Avich]].<ref>British Geological Survey 1:50,000 scale geological map sheet 37W (Scotland) ''Furnace'' 2008</ref> The deposits are especially obvious on Kerrera where they form the bedrock across half of the island.<ref>British Geological Survey 1:50,000 scale geological map sheet 44E (Scotland) ''Lismore'' 1992</ref> These are conformably overlain by [[peperite]] and the [[basalt]]ic and andesitic [[Lorne plateau lavas]]. The ORS on Kerrera and isolated localities around Oban are known for their fossils, particularly fish.<ref>{{Cite journal|last1=Trewin|first1=N. H.|last2=Gurr|first2=P. R.|last3=Jones|first3=R. B.|last4=Gavin|first4=P.|date=November 2012|title=The biota, depositional environment and age of the Old Red Sandstone of the island of Kerrera, Scotland|url=http://sjg.lyellcollection.org/lookup/doi/10.1144/sjg2012-452|journal=Scottish Journal of Geology|language=en|volume=48|issue=2|pages=77–90|doi=10.1144/sjg2012-452|bibcode=2012ScJG...48...77T |s2cid=140575299 |issn=0036-9276|url-access=subscription}}</ref>[[File:Gardenstown Old Red Sandstone - geograph.org.uk - 178600.jpg|thumb|Old Red Sandstone at [[Gardenstown]], Aberdeenshire]]