Complex sentence: The Great Scar Limestone Group consists of a number of different formations except over the Alston Block where a 107m thickness of largely Asbian age limestones and sandstones known as the Melmerby Scar Limestone Formation.
Split into simpler sentences: The Great Scar Limestone Group amounts to around 107m thickness of largely Asbian age limestones and sandstones over the Alston Block. Over the Alston Block the Great Scar Limestone Group is represented only by the Melmerby Scar Limestone Formation.