Input (grade 12): The Blue Lias consists of a sequence of limestone and shale layers, laid down in latest Triassic and early Jurassic times, between 195 and 200 million years ago.
Output (grade 6): The Blue Lias consists of a sequence of limestone and shale layers. It was laid down in late Triassic and early Jurassic times, between 195 and 200 million years ago.