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728 REPORT—1863. 
law regulating the increase of density, as a great number of experiments 
would require to be made extending over a considerable area, -and great 
care that the waters tested are not locally contaminated by contact with de- 
composing rocks. The results of the testing of a great many samples ob- 
tained at various depths over the Hetton, South Hetton, Murton, and Seaham 
estates, extending over an area of about thirty square miles, were described. 
From this it would seem that the line of uniform saltness, so far as the 
above researches go, by no means follows either a line of uniform depth, or 
that of stratification, and does not depend on the contour of the country or 
the line of saturation. 
The water of the greatest density was obtained from the roof of the Hutton 
seam, at Seaton Colliery, at a depth of 1500 feet from the surface, or 1260 
feet below the level of the sea. This density was 1-026, being nearly that 
of sea-water. 
In other parts of this coal-field, however, as at Walker, Framwellgate, 
Butterby, Lambton, Birtley, and St. Lawrence, saline springs of an entirely 
different character are met with at various depths (in the case of Framwell- 
gate and Butterby coming to the surface), and at some of these places the 
springs have been used as brine-springs for the preparation of ordinary 
salt. ‘ 
Various opinions are held by geologists as to the precise structure of the 
Permian series of this district, and their relationship to the subjacent rocks. 
Perhaps, with little exception, all the older geologists, and those not residing 
in this neighbourhood, consider the Permian series of this district to lie un- 
conformably on the Coal-measures, and that the Yellow sandstone and Red 
sandstone beds form a part of the Permian series, and are conformable to the 
overlying Magnesian limestone. 
On the other hand, local geologists, whose opinions, from their opportunity 
of examination and from the attention which they have bestowed on this 
series of rocks, are well worthy of every consideration, are of opinion that the 
Yellow sandstone and Red sandstone beds form part of, and are conformable 
to the Coal-measures, and do not belong to the Permian strata. This view, 
however, does not seem to be borne out by well-ascertained facts; questions 
of conformability, in all cases connected with the Yellow sandstone, must be 
doubtfully entertained, as this rock lies more in ‘hills than in beds; and the 
question of its conformability to the Limestone must be settled by examination 
over an extended area, as, indeed, is essential in order correctly to ascertain 
all questions of conformability. It may be observed, that whilst at Monk- 
wearmouth Pit the Coal-measure strata intervening between the Magnesian 
limestone and the Hutton seam are 1500 feet, at Seaham they are 1100 feet, 
and at Castle Eden only 400 feet. So that at Castle Eden 1100 feet of Coal- 
measure strata have been denuded, and yet the Yellow-sandstone underlies 
the Limestone at each place. 
With respect to the “ Red beds,’’ it would seem to the writers that if they 
can be proved to be independent beds, they must also be conformable to the 
Limestone, resting with it unconformably on the edges of the Coal strata; but 
for several reasons they venture to express an opinion that they do not exist 
at all as independent beds, but are merely the reddened edges of the Coal- 
measure rocks themselves. 
_ The following are the reasons which have led the writers to entertain this 
view :— 
Ist. Beds of ‘‘ Red rocks” are frequently met with below the coal-seams 
in sinking shafts, as is shown at Monkwearmouth, Ryhope, Seaton and Castle 
