96 The Geology of the BaiJicaj/ Line from 



the escarpment to tlie bottom, viz., tlie chalk at the top, the greensand 

 below this, and the gault at the base, has, if you will examine on a 

 nrnp the shajye of the parishes situated on the escarpment, determined 

 this shape, which you will find to be a long parallelogram, of width 

 varying with the size of the parish, but agreeing very much in 

 kngth, and extending from the top of the escai-pment to the bottom, 

 i.e., from the chalk to the gault. It will thus be found that each 

 parish has its share of the chalk, or doAA-n land, on the top ; of the 

 arable land, i.e., the upper greensand, on the slope ; and of the 

 grass, or the gault, at the base. 



The same thing is found to be the case in all simUarly-situated 

 parishes in other parts of England. 



This is a point of much interest, showing how geology can in 

 such cases determine the shape of a parish, but where parishes are 

 situated wholly on one geological formation then other considerations 

 of course step in and the shape is irregular. 



The chalk, being open land, was chosen as the site of very early 

 settlements, and existing parochial boundaries no doubt in many 

 cases perpetuate divisions of the land which existed before the 

 parochial system itself came into existence. 



Greensand and the Water Supply. 



The reason why the villages follow the outcrop of the upper 

 greensand is found in the ease with which water is procured, for 

 the sand lets rain water through very easily. It is then stopped 

 by the gault clay underneath, and causes springs. Sjirings also 

 occui' near the junction of the lower chalk and the greensand. 



Greensand and Sanitation. 



This ease with Avhich water sinks through the greensand should 

 cause far greater caution than as a rule is exsrcised in allowing any 

 cesspits to exist in the upper greensand, or indeed anjnvhere, as 

 they are most dangerous, 



AVe may, it is true, go on offending against sanitary laws with 

 far greater impunity in some soils than in others, though retribution 



