(Duj) Yes, it's chalk, which is why there are no rivers on it, just hundreds of dry valleys. The water sinks in to become groundwater and is in effect a huge subterranean reservoir from which the water is drawn via boreholes. The problem is that it takes ages to top up again after a dry spell but short-term fluctuations tend to be ironed out. (Projoy) Certainly won't give you a running sore.
