Investigating the nature and origins of Gaping Gill Main Chamber, North Yorkshire, UK, using ground penetrating radar and lidar

The paper reports on a first application of ground penetrating radar (GPR) and lidar (LIght Distance and Ranging) in Gaping Gill Main Chamber (GGMC). The GPR image quality is exceptionally good. Sedimentary structures are clearly recognizable down to 30m below the chamber floor. We compare the sequence stratigraphy with the stepped velocity profile and a century of flood history and suggest a link between the sequence of flow directions and the last five interglacial events. In that scenario, the GGMC roof was breached at the beginning of the last Pleistocene interglacial, reversing floodwater flow directions in the chamber. We compare estimated process rates with that time-scale. Lidar surveys provide accurate spatial measurements. The GPR-estimated minimum sediment volume beneath the chamber floor is about 1.8 times the lidar-measured chamber volume above. As a 3-D "base survey", the 2003 lidar data will allow timelapse, or '4-D' monitoring of any future changes in GGMC. © British Cave Research Association, 2005.