MR. E. WILSON ON THE DURHAM SALT-DISTRICT. 761 



43. On the Durham Salt-District. 

 By E. Wilson, Esq., F.G.S. (Head June 6, 1888.) 



The new salt-field in the North of England occupies the low-lying 

 country bordering the estuary of the Tees, situate partly in York- 

 shire, partly in Durham, and bounded by the Magnesian Limestone 

 district of Durham on the north, by the Jurassic hills of Cleveland 

 on the south, and by the German Ocean on the east*. 



At the present time this salt-field has a proved or fairly indicated 

 area of at least twelve square miles. Of this area, however, more 

 than half lies beneath the sea, and is therefore inaccessible by the 

 only system of working at present in operation in the district. 

 Beyond these limits, however, the Durham salt-field has probably a 

 wide extension. Evidences of a limitation of the field in a northerly 

 and also in a westerly direction have, indeed, been obtained ; but 

 what are its boundaries on the south and on the east we have not 

 as yet, and perhaps never shall have, any means of determining. 



Discovery of the Boch-salt at Midclleshorough and Origin and 

 Progress of the Salt Industry in South Durham f. 



In the year 1859, Messrs Bolckow and Yaughan, the celebrated 

 ironmasters of Middlesborough-on-Tees, being in want of water at their 

 Middlesborough Ironworks, had a borehole, 18 inches in diameter, put 

 down to a depth of 1200 feet J. Although large supplies of water 

 were yielded by the more pervious strata passed through in this boring, 

 this water was so highly charged with sulphate of lime as to be 

 quite unfit for the purposes for which it was required. After 

 passing through 70 feet of superficial deposits, which in this district 

 consist of marine warp, river-alluvium, and Boulder-clay, and 

 1136 feet of red sandstone and red and blue marls with gypsum, 

 a bed of rock-salt, 100 feet in thickness, was struck at 1206 feet 

 from the surface, the boring leaving off (in August 1863) in rock 

 described as " limestone and conglomerate containing much salt " at 

 a total depth of 1313 feet 4 inches. 



The discovery of rock-salt in the Tees Yalley was thus a fortuitous 

 piece of good luck. It may be remarked that this was also the 

 case in Cheshire and in Antrim ; but in those instances the discovery 

 of the salt-beds was made in searching for coal. Shortly after its 



* See map, p. 762. 



t The discovery of rock-salt in the Tees Yalley may be said to have been 

 forecast so far back as 1816. In that year Mr. N. J. Winch, in his " Observations 

 on the Eastern part of Yorkshire," read before the Geological Society, referring 

 to the mineral springs of Dinsdale and Croft-on-Tees, said, "I have never heard 

 that any brine spring had its source in this series of strata, though red sand- 

 stone in which gypsum abounds seems a likely locality for rock-salt " (Trans. 

 Geol. Soc. vol. V. 1821, p. 543). 



I For details of this section see Mr. John Marley " On the discovery of rock- 

 salt in the New Red Sandstone at Middlesborough,"Eep. Bi-it. Assoc. 1863, Trans. 

 of Sections, p. 82, and ' Geologist,' 1863, p. 387. 



