6 A new concept of karst development based on hydrogeology and geophysics D6 41 D7 – Lower Bajocian 41 D8 – Upper Bajocian 42 D9 – Lower Bathonian 43 D10 – Middle and upper Bathonian 43 Stratigraphy of the Bajocian south of Poitiers: the cliffs of Passelourdin 44 Conclusion 51 References 51 Chapter 3 • Hydrogeology of the Poitou Threshold 59 T. Gaillard and M. Moreau Aquifers of the Poitou threshold 59 Two main aquifers 59 Piezometric map 60 The supra-Toarcian aquifer 64 Groundwater flow patterns in the supra-Toarcian aquifer 64 Comparison between lineaments and speleological networks 65 Typology of voids in Poitou threshold limestones 68 Pumping tests 71 Conclusion 77 Acknowledgements 78 References 78 Chapter 4 • The Hydrogeological Experimental Site of Poitiers University (France) 81 T. Gaillard Origin of the hydrogeological experimental site (HES) 81 HES description 82 Scientific studies 84 References 85 Chapter 5 • Geophysical methods 87 J.-L. Mari 5.1 Seismic and acoustic methods 89 5.2 3D seismic imaging 92 5.3 Full waveform acoustic logging 98 5.4 Vertical seismic profiles versus full waveform acoustic logging 103 5.5 Electrical methods 107
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