The bedrock of the district consists of some of the oldest sedimentary rock exposed in the British Isles.
The Alleghany Plateau is the north-westernmost division of the Appalachian system; it is an eroded mass of sedimentary rock sloping north-westward to the Prairie and Lake Plains and reaching south-west from the south-western part of New York state through Tennessee and into Alabama.
The bedrock of the district consists of some of the oldest sedimentary rock of the district consists of some of the oldest sedimentary rock exposed in the British Isles.
