Page:Transactions of the Geological Society, 1st series, vol. 4.djvu/62



About thirty years since a brine spring was discovered at Birtley colliery 76 fathoms below the surface, in driving a water level through a slip of 4$$\scriptstyle \frac 12$$ fathoms throw. The spring being found to produce 26400 gallons of water in twenty-four hours, extensive salt works were erected on the spot, which are still carried on with success. Within 50 or 60 yards north of the slip, from which the spring issues, the Birtley dyke before mentioned crosses the strata from east to west, casting up the coal measures on the northern side 99 fathoms; and the slip having a south-eastern direction probably meets the dyke and is a branch from it. The water level is driven in a bed of blue shale containing ironstone in beds and in nodules. The analysis of the water by Mr. G. Woods is as follows.

Before the publication of Camden's Britannia in 1607, a brine spring had been observed to issue from the rocky bed of the Wear at Salt water Haugh near Butterby; for in that work it is first mentioned. In 1684, Mr. Hugh Todd drew up an account of this