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This edit changed it on the basis that "Devonian period finished 359 m.y.a. so it must be Carboniferous strata", but I've undone the change as UofE source has "Devonian sandstones deposited on a broad coastal plain periodically flooded by the sea about 345 million years ago." Tried a couple of textbooks which don't give that specific detail, a search didn't find support for Carboniferous at Siccar Point, this describes the rocks as Devonian while noting Carboniferous sandstone at Pease Bay, along the coast to the north. The NCSE Report has "The vertical sediments at Siccar Point are Silurian greywacke, a gray sedimentary rock formed approximately 425 million years ago ... By about 80 million years later ... the raised greywacke had eroded and parts were again submerged in the ocean. Erosion of the nearby Caledonian Mountains produced reddish sandstone sediments (Old Red Sandstone of the Devonian) that were deposited horizontally over the vertical greywacke sediments (of the Silurian)." That reaffirms Devonian, of a period earlier than 345 million years ago. Identification with Carboniferous would appear to be borderline, we could use the NCSE Report to refine our statement if we can't find a better source. . dave souza, talk 18:00, 19 August 2015 (UTC)
Okay, I understand why you've reverted it but it leaves us as before in what is really an unsatisfactory situation where the given age is most certainly Carboniferous (a period, as we each know, stretching from 359-299mya on the present ICS scale) even as the texts you refer to say Devonian. Perhaps someone else can assist? Geopersona (talk) 11:56, 31 August 2015 (UTC)
Tried more searching today, and found a couple of recent sources changing the mya and keeping the Old Red Sandstone Devonian, while the greywacke remains with the ancient Welsh tribe. Think that should do it, "Go it Ancient B's!" . . dave souza, talk 19:21, 31 August 2015 (UTC)