Torridonian

The Torridonian is a sequence of Mesoproterozoic to Neoproterozoic sedimentary rocks in northwestern Scotland, composed primarily of sandstone and related deposits, dating from roughly 1.2 billion to about 544 million years ago and spanning the late Precambrian. It rests unconformably atop the much older Lewisian basement rocks and lies beneath younger Cambrian to Ordovician formations. The rocks outcrop along the northwestern coast of Scotland and parts of the Inner Hebrides, from the Isle of Mull in the southwest to Cape Wrath in the northeast. The sequence is subdivided into the Stoer, Torridon and Sleat groups, each with a distinct depositional history, and recent detrital zircon analysis has linked these rocks to the Morar Group of the Scottish Moine, placing the Torridonian within the larger Wester Ross Supergroup and providing insight into Precambrian mountain-building events across northern Scotland. This entity documents the Torridonian specifically as a geological formation, a very ancient Precambrian sandstone sequence.