WR. E. WILSON ON THE DURHAM SALT-DISTRICT. 765 



It is intended to carry the Seaton Carew boring to a total depth 

 of 2000 feet, in order to determine whether or not productive measures 

 of the Durham Coal-field extend beneath the Permian and Triassic 

 rocks in this direction. Whatever be the result, this trial-boring 

 will always be one of very great geological interest, not only fi^om the 

 light it will throw upon this important question, but also from its 

 furnishing us for the first time, in one complete vertical section, 

 with the entire series of the Magnesian Limestone of Durham*. 



Further successful explorations for rock-salt have also been 

 recently conducted south of the estuary of the Tees. The Middles- 

 borough Estate Co., Limited, have proved the salt-bed 90 feet in thick- 

 ness at a depth of 1341 feet from the surface at North Ormesby, 

 three quarters of a mile (1200 yards) due south of Messrs. Bolckow 

 and Co.'s Middlesborough boring. The Cleveland Salt Company (for- 

 merly Messrs. Bolckow and Vaughan) have sunk a well on the Tees 

 foreshore, near the Eston Ironworks, about 2| miles east of their 

 Middlesborough well, and found the salt-bed 81 feet in thickness at a 

 depth of 1570 feet from the surface f. The salt-bed (86 feet) has 

 also been proved at the Imperial Ironworks, half a mile nearer 

 Middlesborough, at about the same depth. In the year 1887 there 

 were, according to Sir Lowthian Bell, no less than twenty wells in the 

 Durham district from wdiich salt in the form of brine had been 

 raised, although seven of these were then disabled through accident. 

 The annual production of salt from these wells in that year has been 

 estimated at 150,000 tons, and for the present year at 200,000 tons 

 or thereabouts. Seeing that the demand for this substance at the 

 soda-works of the neighbouring district is at the present time very 

 considerably in excess of this amount, there can be very little doubt 

 that, the natural supplies being ample, the above output is capable 

 of very considerable expansion in the future. 



Stratigrapliical Position of the Saliferous Rocks of the Durham district. 



As in other cases where our knowledge of the stratigraphy of a 

 district mainly depends upon the evidence afforded by deep borings, 

 the determination of the geological age of the saliferous rocks of the 

 Durham district is by no means free from difficulty. We must not 

 therefore be surprised to find that very diverse and conflicting 

 opinions have already been expressed, and that at the present time 

 a good deal of confusion exists on the subject. I propose in the first 

 place to briefly review these opinions, and afterwards to con- 

 sider in a little more detail the particular view which I believe to 

 be the correct one. 



In a paper read before the British Association in 1863, Mr. John 

 Marley described the discovery of rock-salt at Middlesborough by 



* Since this paper was read the boring at Seaton Carew has been continued 

 and is still proceeding. The Magnesian Limestone has been proved to have a 

 total thickness of 878 feet at this point. At a deptli of 1400 feet from tlie 

 surface Carboniferous rocks were entered, and on Sept. 29tJi, 1888, had been 

 proved to a depth of 400 feet, or a total depth of 1800 feet from the surface. 

 These rocks consist of grey and red sandstones with dark bituminous shales 

 with two thin coal-seams, and evidently belong to the Coal-measures of Durham • 

 but, so far, no workable coal has been reached. 



t See Appendix, p. 778. 



Q.J.G.S. No. 176. 3e 



