Geology
The geology of the Blackdown Hills together with the adjoining East Devon AONB is unique in south-west England, forming part of the only extensive outcrop of Upper Greensand in the region.
The Blackdown Hills form a flat plateau dominated by hard chert bands, made up of clay with flints, of Upper Greensand with some remnants of chalk. The cretaceous rocks rest over eroded Jurassic and Triassic beds, with an outcrop of Rhaetian beds. In the western areas the Upper Greensand is devoid of calcareous material but the sands yield fossils of marine bivalves and gastropods (snails) preserved in silica.
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