ON THE CIRCULATION OF UNDERGROUND WATERS. 



397 



Fine-grained soft red sandstone, 31 ft. 



Round-grained soft red sandstone. . 



Red sandstone. 



Rather hard red sandstone. 



Soft red sandstone. 



Coarse sandstone. 



Red sandstone, very soft. 



Appendix to Triassic Report. — Experiments on the Filtration of Sea Water 

 through Triassic Sandstone. By Mr. Isaac Roberts. 



In the town of Liverpool several million gallons of water are pumped 

 daily out of wells sunk in the Pebble Beds of the Bunter sandstones. 



The whole area from which this quantity is withdrawn is covered by 

 pavements, buildings, and a thick bed of boulder clay, so that it is not 

 possible for much, if any, of this large daily supply of water, to percolate 

 from the surface into the sandstone. Nor are there within the sandstone 

 rocks of this neighbourhood open fissures or channels through which the 

 water could freely pass from distant sources into the wells ; nor are there 

 subterranean reservoirs of water (leakages from pipes and sewers excepted) 

 from which the supply could be drawn. Where, then, does the water 

 come from ? 



In a paper which I read before the Geological Society of Liverpool in 

 1869, I suggested that most of it must flow from the Liverpool Docks 

 and the River Mersey by passing through the mass of the rock ; and that 

 the sandstone rock must filter, or chemically neutralize the salts held in 

 solution in sea water. In the paper referred to, I gave analyses of the 

 water drawn from several wells in Liverpool and the neighbourhood, to 

 show that there is a gradual constant accumulation of salts in the water 

 obtained from all the wells respectively. I will here give one example, 

 which shall be typical of the rest. The well is situated in Rainford 

 Square, distant 500 yards from the. nearest dock, and 800 yards from 

 the River Mersey. The analyses are given in tabular form, to facilitate 

 comparisons : — 



WATER FROM THE WELL, RAINFORD SQUARE. 



