A nonconformity is a surface that separates two rock masses of different types and ages. Older igneous or metamorphic rocks are exposed to erosion for some time before younger sediments are deposited upon them. A nonconformity between eroded Dalradian rocks and overlying Devonian sediments is exposed here at Fladdabister and continues north around the coast. The oldest Dalradian rocks formed from sands that were laid down within marine basins as an ancient continent began to split apart about 730 million years and the Iapetus Ocean was born. Between 480 and 390 million years ago the Iapetus closed again, as continents on either side collided and forced up the huge Caledonian Mountain chain. The sandstones were metamorphosed to psammite and tilted almost vertically. Steep mountain slopes, of psammite and other rocks, were exposed to the elements and eroded – perhaps for millions of years. Between 394 and 384 million years ago, during the Devonian Period, eroded blocks of psammite, granite and quartzite, built up to form scree on these mountain slopes. The scree consolidated to form thick deposits of coarse breccia. At Fladdabister, and further north at Quarff, this breccia lies on top of the near vertical psammites of the Caledonian mountains.
At Fladdabister sandstones are laid on the eroded surface of tilted beds of metamorphic rocks - a junction known as an nonconformity.
Directions
Fladdabister is in the South Mainland north of Cunningsburgh
Take the A970 and turn off to Fladdabister
Park beside the cluster of ruined buildings just north of the burn
Follow the public access route along the burn until you cross it. Then head up the hill on the left to the lime kilns
Follow the coast to the left for a few metres until you reach the inlet beneath the rocky mound
Please note that this walk contains a two-step stile