288 J. 8. Brown — Relation of Sea Water 



irregularities in the distribution of salt and fresh water 

 are easily accounted for by the local geology, but it is 

 clear (1) that salt water actually underlies the land at a 

 depth of 100 to 200 meters below sea level over a belt 

 several miles in width ; (2) that the depth to salt water 

 is greatest where the land and the water table are highest ; 

 (3) that salt water rises under areas of low ground, or 

 rather under areas having a depressed water table, such 

 as the polder of the old sea of Haarlem. The general 

 line of contact between salt and fresh water is very 

 regular, however, and the zone of gradation or diffusion 

 is surprisingly thin. 



Laboratory experiments by D'Andrimont, 15 a Belgian, 

 also gave results very much like thos«e from Holland. 



Effects of pumping on salt content. 



In the work near New Haven 23 pumping plants within 

 500 feet of the shore were examined. The water at ten 

 of these plants was highly contaminated with sea water, 

 and that at three or four others was contaminated 

 slightly. The greatest distance from the shore at which 

 high contamination was noted was 400 feet. In general, 

 the plants that supplied the larger amounts of water were 

 more highly contaminated. 



All the evidence regarding the effect of pumping tends 

 to one conclusion — that if more water is removed than 

 the contributory area supplies, the wells become salty. 

 This statement is as true for domestic wells drawing from 

 a small intake area as for pumping plants supplied with 

 the underflow of a large drainage basin. Thus the 

 Beattie dug well, which probably drains about 1 acre of 

 sand (stratified drift) at the end of a small island, origi- 

 nally yielded good water, but the demands of one family, 

 when increased by the installation of a household water 

 system, were sufficient to overtax the well and make the 

 water salty. 



The best data regarding the limiting rate at which 

 water may be pumped from a given contributory area 



15 D 'Andrimont, Bene : Note preliminaire sur une novelle methode pour 

 etudier experimentalement 1 'allure des nappes aquif eres dans les terrains per- 

 meable en petit, Annales de la Societe geologique de Belgique, t. 32, 

 Memoires, pp. 115-120, Liege, 1906. 



