SALTPAN NEAR HAAGKNSTAD. 217 



The next problem is "Where does the salt come from?" 

 As against its coming- from below in the form of springs or by 

 capillary attraction I adduce the following facts. 



1. Salt beds are unknown to occur in the Ecca series. 



2. No trace of rock salt has been found in deep borings at 

 Kroonstad, which is on the same line of strike as the salt pan. 



3. Wells sunk in the pan show a diminution in the per- 

 centage of salt the deeper they are sunk, except for the first 

 few feet. 



4. The warm spring supplying the baths, whose water must 

 have risen some hundreds of feet, if we are to take its tempera- 

 ture as an indication, is, to say the most, only brackish. This 

 brackishness would result from the water's flowing through 

 the sand, which contains a large quantity of salt. 



Neither can the salt come from a layer situated in higher 

 ground around the pan. If such a layer ever existed it would 

 have been carried away by solution long ago. 



The salt, then, is evidently collected from the ordinarv sur- 

 face rocks of the district. After a heavy rain many hundreds 

 of tons of water, which has run over a large catchment area, 

 are collected in this great flat pan. The only outlet for the 

 water is above — by evaporation — the salts remain behind. 

 The present collection of the pan floor of one or two feet of 

 mud impregnated with salt is the result of evaporation that 

 has been carried on for thousands of years. 



The dams on the side of the pan contain fresh water; there 

 IS no salt deposited in them, but this is obviously because they 

 have existed for comparatively only a few years. 



Many hundreds of tons of salt are taken from the pan every 

 year, and it would be interesting to know for how long this 

 abstraction could take place at a given rate. 



This would be a fairly easy determination. The depth of 

 mud overlying the shales is fairly uniform, and its average 

 depth could readily be obtained. The average quantitv of 

 salt in each cubic foot of mud could be calculated bv deter- 

 mining the quantity in numerous specimens. This quantity 

 multiplied by the number of cubic feet in the pan will give 

 the total amount of salt. 



Besides the question of how much salt the pan contains, 

 there is the interesting matter of evaporation of the brine. 

 The system of natural evaporation in sail cloths is too slow to 

 allow a large development of the industry. What is needed is 

 cheap coal to supply the heat for artificial evaporation. 



Little doubt now exists as to coal underlying practicallv the 

 whole of the Free State. It reaches the surface at the base 

 of the Ecca series at Vereeniging, and in several places in the 

 East Rand; also near the top of the same series in the west 

 of Natal. 



Coal, then, probably lining the bottom of the syncline, exists 

 in the district of the Salt Pan. But this stratum will probably 

 be found to lie too deep for pracitcal mining purposes. Other 

 layers, however, lying in the middle of the series mav be dis- 

 covered. 



