 St Cuthbert's Swallet was formed by the erosive action of water flowing beneath the water-table at considerable depth (so called "phreatic development").St Cuthbert's Swallet is a classic example of a deep phreatic cave system, containing inclined bedding plane mazes at many levels, fault-guided rifts and some significant chambers.Nine successive phases of sediment deposition, stalagmite deposition and stream erosion have been recognised in St Cuthbert's Swallet, providing an exceptional record of environmental change through the
warm and cold phases of the Ice Age.