SALT AND COAL IN THE TEES DISTRICT. 491 



Comparing the two borings as above, and especially the details given 

 in the Appendix (p. 492 et seqq.), it will be seen that, allowing 24 feet 

 for difference in altitude, the results are practically identical. The 

 Upper Keuper Eed Marls with gypsum are absent from both, and in 

 neither is any salt met with. The Magnesian Limestone lies 4 feet 

 lower in No. 1 than in No. 2 : that is, in the direction of dip. The 

 prevailing opinion regarding the horizon of the salt-rock in Durham 

 no longer needs defence, but it may be well to remark in passing 

 that the cores brought up from near the bottom of Messrs. Bell 

 Brothers' trial-boring in 1876 presented a very different aspect 

 from those obtained from Magnesian Limestone in these Whitehouse 

 borings, as well as from that proved at Seaton Carew, where it was 

 at its best — 878 feet, the thickest section in County Durham. 



3. Eight miles due east of Whitehouse boreholes, on the opposite 

 margin of the Tees Salt-field, a borehole was being drilled at about 

 the same time, and should be noticed here. It was put down on 

 Lackenby foreshore, about 1 mile (6000 feet) north-east of Eston 

 borehole, the most easterly shown on Mr. Wilson's map.^ A vertical 

 section has already appeared,^ but as no cores were brought out 

 by the method employed, the Eed rocks have to be apportioned so as 

 to approximate most nearly to contiguous borings executed with 

 the diamond rock-borer. The following abstract may suffice for 

 our purpose : — 



ft. in. 



Surface-deposits 13 



Upper Keuper Eed Marls 495 



Eed Sandstones and Marls 869 



Saiiferous Marls 266 



Anhydrite 29 



'EottenMarl' 13 



Eock-salt 119 



Anhydrite 2 



1806 



This borehole is important as adding 1 mile to the width of the 

 Tees Salt-area. The upper surface of the salt here is 116 feet 

 lower than it is in the Eston borehole : the salt-bed also is thicker, 

 thus confirming previous anticipations as to both these items 

 increasing with the south-easterly dip.^ Every one of the fifteen 

 boreholes or wells situated south of the River Tees passes through 

 the Upper Gypseous Marls, i. e. the Upper Keuper Bed Marls with 

 gypsum (at Liuthorpe the gypsum bed, five feet in thickness, was 

 reached at about 350 feet) ; and ail have proved the salt- seam in 

 good workable thickness. But while they agree in indicating a 



1 Quart. Jouru. Geol. Soc. toI. xliv. (1888) p. 762. 



'^ Brit. Assoc. Eeport (Leeds Meeting), 1890, p. 367. 



^ Quart. Journ. Geol. Soc. vol. xliv. (1888) p. 775. The above figures exceed 

 somewhat the depth and thickness of salt estimated by the writer in 1880, but 

 the ground was not then so well-known as now. 



