488 



MR. T. TATE ON RECENT BORINGS FOR 



35. I»J'oTES on Eecent Borings for Salt and Coal in the Tees 

 District. By Thomas Tate, Esq., JF.G.S. (Bead June 22nd, 

 1892.) 



Since the publication of Mr. E. Wilson's exhaustive paper on the 

 Durham Salt- district/ commercial enterprise has given an impulse 

 to exploration, so that now the number of boreholes is over sixty. 

 Most of these simply emphasize the knowledge derived from earlier 

 work, with which they coincide. Three or four, however, may 

 possibly contribute a few geological facts of interest, in relation to 

 (a) the area of the Tees Salt-field and (h) the determination of the 

 southern limit of the Durham Coal-basin. 



1. WTiiteTiouse, Norton^ No. 1 horeliole. — This borehole is 3J- miles 

 due west of Messrs. Watson and Scrafton's Stone Marsh borehole, 

 the most westerly boring shown on Mr. Wilson's map.^ Its site is 

 76 feet above sea-level, as proved by a neighbouring bench-mark. Pull 

 details of the strata bored through will be found in the Appendix to 

 the present communication. The horizon of the rock-salt in this 

 district lies at the base of the Saliferous Marls, and the layer of 

 salt invariably has above it a bed of anhydrite, usually underlain by 

 a stratum of red marl left in a rotten state by the dissolving out of 

 some constituent : this is the ' rotten marl ' of the workmen, to the 

 presence of which is due the collapse of many brine-wells. Below 

 the beds of pure and impure rock-salt comes the lower anhydrite, 

 BO that the salt-bearing stratum, wherever present, is sandwiched 

 between two layers of anhydrite, and its horizon is never a matter 

 of doubt for anyone practically acquainted therewith. 



This boring, after piercing through 115 feet of Drift deposits and 

 151 feet of Bed Sandstones and Marls, struck the Saliferous Marls, 

 as follows : — 



ft. in. 



Bed marls with gypsum 130 



Anhydrite 10 



Bed marl and gypsum (compact) 17 2 



Horizon of rock-salt , 



Anhydrite 17 9 



Gypsum 3 



177 11 



The presence of the bed of compact red marl foreshadowed the 

 absence of salt from this area. 



It is sometimes suggested that percolating water may have re- 

 moved the missing salt, but if a cavity had been so formed here the 

 drilling tool would have ' dropped ' ; this, however, did not occur. 



■^ 'The Durham Salt-district, 

 p. 761. 



Quart. Journ. 



Geol. See. vol. xhv. 

 ^ Ibid. p. 762. 



(1888) 



