 Several areas have outcrops of slates and between St Audries and Kilve , younger rocks of the Jurassic Period can be found . This area falls within the Blue Anchor to <unk> Site of Special Scientific Interest ( SSSI ) and is considered to be of international geological importance . At Kilve are the remains of a red brick retort , built in 1924 , when it was discovered that the shale found in the cliffs was rich in oil . At Blue Anchor the coloured alabaster found in the cliffs gave rise to the name of the colour " Watchet Blue " . 
