The geologic folds comprise three major bands (lithological units) of building that date from three epochs: the Lias (Early Jurassic), the Dogger (Middle Jurassic) and the Malm (Late Jurassic) geologic periods. Each era of folding reveals effects of previously shallow marine environments as evidenced by beds with carbonate sequences, containing abundant bioclasts and oolitic divisions between layers (called horizons).
