Geograph - photograph every grid square

In Scotland where one is so used to seeing younger rocks thrust over older ones by the dramatic (if long drawn out) collision of continents, it's good to find a classic unconformity where the younger rocks (in this case Triassic conglomerates) were laid down over the top of an existing, ancient landscape. The lower rocks (grey, layered, fine-grained) are Psammites of the Moine Series - ancient impure sandstones metamorphosed by heat and pressure, then raised to the surface and eroded. They formed shoreline rocks as the sea covered them and deposited sand and pebbles which, with deeper burial, became the conglomerate rock you see above the eroded caves and below the grass. The uneven boundary between the two rock types shows the shape of the rocky shore before its burial. More recently again, in Tertiary times, as Europe and North America started to separate, the whole lot was buried deeper by lava flows. Erosion works constantly, and here they all are again exposed to view as the sea cuts away the land, leaving scattered boulders not only of the conglomerate and the psammite, but also of the basalt from the cliffs seen in the distance.