I don’t know, Interesting question if water is the factor. here in Az we are almost all sedimentary sandstone and dry as a bone deep with very very few aquifers. Yet we have several vortexes like the well known Sedona area.
In a now dry area, ancient water bodies could have left salts behind, so that would still be a conductivity factor.
The Sedona Vortex?? And maybe the iron content of the soils and rock is a factor? I know that there are minerals such as quartz that are used to clock electrical clocks and circuits. (pizoelectric effect.) Avoiding that rabbit hole. Thats another thread.