GSB Prospection Ltd

	Electromagnetic EM31 The EM31 maps geological variations, groundwater contaminants or any subsurface feature associated with changes in the ground conductivity using a patented electromagnetic inductive technique that makes the measurements without electrodes or ground contact. With this inductive method, surveys can be carried out under most geological conditions including those of high surface resistivity such as sand, gravel and asphalt. The effective depth of exploration is about six metres, making it ideal for many geotechnical and groundwater contaminant surveys.
	EM 61 A time domain metal detector which detects both ferrous and non-ferrous objects. The advantage of this instrument is that depth can be calculated, up to around three metres. This technique has been used successfully to locate buried aircraft.
	In 2005 GSB Prospection Ltd surveyed at Warton Marsh, Preston, Lancashire as part of Time Team. This plot shows one of the Douglas A-26 Invader US bomber planes which crashed in 1944. The deeper red being the engine.
	EM 38 This technique measures magnetic susceptibility and the electrical component of the soils simultaneously. The EM-38 can provide rapid surveys with excellent lateral resolution
	Targets Detected Buried Aircraft Unexploded munitions and explosives of concern Storage tanks Gravel banks and palaeochannels