WORGRET HILL AND WAREHAM WATER SUPPLY. 165 



boring in the Bagshot Series is not likely to improve matters, 

 and a similar difficulty would most propably arise if a lower 

 water-bearing stratum in the Bagshots was tapped. To purify 

 the existing supply of water is an engineering, rather than a 

 geological, question. 



" When we come to speculate on what lies below the termina- 

 tion of the borehole (215 feet from the surface), it is almost 

 impossible to predict what may be the thickness of the 

 remainder of the Bagshot Beds. Below the pipeclay series it is 

 almost certain that another sandy series would be encountered 

 as constituting the base of the formation, and there may be 

 bands of iron grit such as occur on this horizon at many places 

 in the Isle of Purbeck. None of the Government geologists, so 

 far as I know, give us any assistance in estimating the thickness 

 of the Bagshot Beds at their full development in Dorset. 



" The Lower Tertiaries. We may naturally conclude that 

 both the London Clay and the Reading Beds will have to be 

 encountered ere the Chalk can be reached. Very little is known 

 about these beds, which are best studied, perhaps, on their 

 outcrop in the Wool district. In a borehole section it may not 

 be very easy to distinguish between Bagshots and London Clay, 

 as the latter formation in this country consists largely of sand. 

 Probably the most distinguishing feature of the London Clay is 

 the amount of black flint pebbles which it contains, and which 

 are sometimes cemented by iron-oxide into a most intractable 

 conglomerate. The Reading Beds are also mainly sandy, but 

 side by side with these sands are developments of mottled clays 

 largely used for brick-making. A total thickness of 100 feet for 

 the London Clay and Reading Beds is, perhaps, fairly approxi- 

 mate. It is quite possible that some of these Lower Tertiaries 

 may contain good water-bearing beds." 



" On the possibility of obtaining water from the Chalk. There 

 would probably be no intention on the part of the Borough of 

 Wareham to sink a well to the Chalk under any circumstances. 

 But if an artesian supply of water could be obtained it might 

 prove an advantage. Certainly the shape of the trough of 



