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



apart on the south bank of the Tees is certainly hopefully suggestive 

 of a wide distribution. It is probable that this mineral underlies 

 a large area of the low-lying ground south of the estuary of the 

 Tees, and it is quite possible that it extends beyond that region and 

 beneath the Cleveland JffiUs of Yorkshire. Owing, however, to the 

 prevailing south-easterly dips of the Secondary rocks of this part 

 of England, and the consequent coming in of higher measures, the 

 saliferous beds of the Trias and rock-salt can only be looked for 

 at very considerable and constantly increasing depths the further we 

 proceed in that direction. In the country north of the Tees, where 

 the inclination of the New Hed Sandstone is generally very small, 

 viz. 2° to 3°, and in some portions of the district almost nil, the 

 Salt-rock is found at depths of from 1200 to 900 feet or less. In 

 the vicinity of the Tees the dip appears to increase to about 5°, so 

 that at Ormesby and Eston, close to the south bank of the river, 

 its depth from the surface is more considerable, viz. 1350 feet and 

 1570 feet respectively. South of the Tees the average inclination 

 of the strata appears to be about 3°. Eeneath the Cleveland Hills 

 the greatest of these depths would be considerably exceeded, seeing 

 that, partly on account of the dip and partly on account of the rise 

 of the ground, the whole or the greater portion of the Lias, as well 

 as almost the entire series of the Triassic rocks of the district, would 

 have to be passed through before the rock-salt (if present) could be 

 reached. 



We are now in a position to indicate approximately what these 

 depths would be. At the Cleveland Salt Company's Eston boring 

 the salt-rock is reached through 1570 feet of Keuper marls and 

 sandstones. At the gypsum-pit, midway between Eston Junction 

 and the Eston Ironstone Mines, the highest stratum of the Keuper 

 marls was reached at a depth of 190 feet from the surface, or about 

 154 feet below the sea-level*. Taking the dip between these two 

 points as 3° S.E., and assuming that no faults intervene to affect 

 our calculations, we should have to add 120 or 130 feet to the Eston 

 salt-works section to arrive at the full thickness of the Keuper rocks 

 down to the rock-salt. This would give 1700 feet, and the full 

 development of the Triassic series, including the saliferous beds at 

 the base, as probably 1900 feet or thereabouts. According to Messrs. 

 Tate and Blake f, the Lias and Rhaetics beneath Eston Moor attain 

 a maximum development of 1325 feet. Adding this to the Triassic 

 strata overlying the salt- bed, we find that in this portion of the 

 Cleveland district any wells sunk to the rock-salt, granting it to be 

 present, would have to be at least 3000 feet deep. It has been supposed 

 by some geologists that productive coal-measures underlie the Jurassic 

 uplands intervening between the Durham and Yorkshire coal-fields, 

 although the opposite view has generally been taken (rightly, I 

 believe) by most of those who are competent to speak on the subject. 

 This is a question entirely beyond the scope of the present paper, 

 and into which I do not intend to enter, beyond calling attention 



* ' The Yorkshire Lias,' 1876, p. 30. 

 t Ibid. p. 193. 



