Candidate geological Sites of Special Scientific Interest (SSSI) have been identified through the Geological Conservation Review (GCR), a systematic site selection exercise carried out throughout Great Britain between 1977 and 1990 (Ellis et al, 1996).
The purpose of the GCR was to systematically identify the key geological sites in Britain. The series as a whole reflects the great range and diversity of British geology.
The Joint Nature Conservation Committee (JNCC) is now responsible for coordination and publication of the results of the GCR.
Three distinct criteria were used to select GCR sites:
Assessment and subsequent selection of sites was undertaken on the basis of a series of blocks which may be based on time, subject or regional divisions or combinations thereof. Examples of GCR blocks include Precambrian of England and Wales, Cambrian, Aalenian-Bajocian, Marine Permian, Tertiary Mammalia, Quaternary of South-West England, Caves of Great Britain and Karst of Great Britain.
Sites were selected in consultation with academic experts in the various fields. Once selected, a GCR site is then proposed as a potential SSSI. It is only when a site is approved and confirmed as an SSSI that it receives full legislative protection.
In addition to the SSSI designation, there are about forty five National Nature Reserves (NNRs) in England with nationally important geological interests. Some, such as Wren's Nest NNR, Dudley, West Midlands, have been declared as NNRs primarily or exclusively for their geological interests. Others, such as Lindisfarne NNR, have been declared primarily for their biological interests but also contain important geological sites.