714 BEPORT— 1887. 



of this kind do not give rise to the reports wMch are met with in the newspapers. 

 The first reported destruction of a mine was in 1760, and from that date to the 

 end of the eighteenth century every two or three years a mine collapsed. In the 

 present century, at considerable intervals of time, collapses of mines have occurred, 

 but these with scarcely an e.vception were old abandoned ' top ' mines. 



The subsidences which are so destructive in the town of Northwich and the 

 neighbourhood are entirely caused by the pumping of brme for the manufacture of 

 white salt. It was only about 1770 or shortly afterwards that the first sinking was 

 noticed ; since that date subsidence has gone on very rapidly, and much destruction 

 of property has resulted. Large lakes or ' flashes,' one of more than 100 acres in 

 area, and of all depths up to 45 feet, have been and are being formed. Prior to 

 1770 not more than 30,000 tous of salt were sent down the Weaver navigation; by 

 the end of the century it reached 100,000 tons, and in 18S0 had increased to 

 1,087,000 tons. The whole of this salt was taken ofi" the surface of the first bed 

 of rock-salt by the solvent action of water. lu fact, water is the instrument used 

 to mine and carry off" the salt to the pumping centre. The brine pumps set up a 

 circulation of the salt water or brine lying on the rock-salt, which flows to the 

 pumping centres. The brine thus removed is replaced Ijy fresh water, which on its 

 passage to the pump saturates itself, taking up sufficient salt to make a solution con- 

 taining about 26 per cent, of salt. This continual removal of salt from the surface 

 of the rock-salt lowers it, and the overlying earths either follow the diminishing 

 surface continuously or else after remaining suspended for a time suddenl}' fall 

 into the cavity from which the water has extracted the salt. The brine currents 

 on their waj- to the pumping centres form deep valleys or troughs, and the surface 

 of the ground overlying forms a facsimile of these hollows. Tlie property on the 

 sloping sides of the valleys is pulled to pieces and destroyed ; the windows and 

 doors aU get out of form owing to the unequal sinking of the various portions of 

 the house. When, owing to the difliereut nature of the marls and the abundance 

 of sand overlying them, a sudden sinking takes place, the hole extends to the 

 surface and swallows up anything upon the surface — as a horse in a stable, barrels 

 of beer in a cellar, or water-butts and other utensils in a j^ard. The damage done to 

 property is enormous, but thus far no human life has been lost. The most serious 

 part of the matter is that the brine-pumper takes not only his own salt in solution, 

 but that of all his neighbours over whose salt-beds the water flows, and neither 

 asks their consent nor pays them for the salt thus obtained. Worse even than 

 this, tlie owner of the property overlying the brine ' runs ' sufl'ers most serious 

 damage to buildings, &:c., but can obtain no compensation because amongst the 

 number of brine-pumpers he cannot prove who is doing the particular mischief 

 complained of. This peculiar phenomenon of subsidence in the salt districts is 

 worthv of more consideration than it has hitherto received from scientific men. 



7. Places of Geological Interest on the Banhs of the Saskatchewan, 

 By Professor J. Hotes Panton, M.A., F.G.S. 



The writer, in this paper, after referring to some of the marked geological 

 features which characterise the three great prairie steppes of the north-west, 

 proceeds to describe two localities more particularly, viz. the vicinity of Medicine 

 Hat, situated on the banks of the Saskatchewan 060 miles west of Winnipeg, and 

 a locality near Irvine Station, 20 miles east of Medicine Hat. 



From Medicine Hat much coal has been obtained and sent to AVinnipeg, and 

 several interesting fossils have been found, consisting chiefly of shells allied to 

 the genus Ostrea and fragments of petrified wood. The deposits are identified as 

 belonging to the Belly Eiver series, an American division of the Cretaceous system. 



The coal is llgnitic in character, showing considerable water and ash, with a 

 tendency to disintegrate when exposed to the air. Contrasted with coal obtained 

 nearer the mountains, it is much softer. 



Two seams occur, separated by about 40 feet of clay, shale, &c., with a bed of 

 Ostrea and a thin coal. The upper seam is 4 feet 8 inches thick, the lower seam 



