Taken from The History, Topography, and Directory of the County Palatine of Durham by Francis Whellan. Second edition published in 1894.

These are few and far between as compared with most coal fields; and the whin, or basaltic dykes, which traverse the district in an east-south-east direction - although they injure the coal on both sides of them to a distance of some yards - are not found to derange and interfere with them, as they do in Scotland and South Staffordshire. Among the ordinary faults the most remarkable is the great 90 fathom dyke, which - appearing on the coast near Cullercoats, where it displaces the strata to that amount - ranges past Gosforth to Blaydon, and then entering on the more hilly ground, may be traced westward through the limestone range to the new red sandstone in the neighbourhood of Carlisle. Along this part of its course the throw, though variable, is sufficient to inlay, as it were, on its north side, a long strip of Coal Measures, and thus to give rise to the collieries of Stublick, Midgholm, Tyndal Fell, &c.

The variations in quality of the seams as they range through this extensive field give rise to different commercial applications. The best "household coal," commonly called after the well-known Wallsend pits, extends from the Tyne to the Wear, and occupies another area about Bishop Auckland. The denser white-ash steam coal characterises the district beginning some five miles north of the Tyne; whilst the tender coals, which form an admirable coke, are largely worked all along the line of the outcrops on the west, from Wylam and Ryton down to the outskirts of Raby Park.

The total production of the Durham and Northumberland field, which in 1854 was 15,420,615 tons; in 1864, 23,284,367 tons; in 1870, 27,613,539 tons; in 1888, 37,666,720 tons, is for the year 1891 no less than 39,138,382 tons. Of this enormous output 29,807,523 tons, the value of which at the pit reaches a total of £10,387,905, was raised in Durham County alone. This extraordinary increase is in great part due to the rapid development of the Cleveland iron district and to the huge quantities of Durham coke which are now conveyed to the western coast for the smelting of the hematite ores.

From a return issued by the Home Office, there are in the Durham district 225 mines, with 72,272 workers, of whom 57,994 are engaged below the surface.

The astonishing in crease in the consumption of coal within the last half century has kept pace with the advancement of various arts and sciences, and has necessitated a constant improvement in the method and appliances used in its extraction. Our knowledge of the mineral resources of this country has during the same time been placed on a footing so much more definite than formerly, as to excite in the reflecting mind conversant with the heavy drain now making on our coalfields, a reasonably founded anxiety as to their duration.

Contented security may in its ignorance of the facts assume that the coal seams are "practically inexhaustible," but a fair examination of the above statistics sct forth, and of the local conditions of our coal-bearing districts, will show that at least the time for prudent forethought has arrived.

"We are drawing," as an able writer has well put it [Mr. Jevons "On the Coal Question"], "ore and more upon a capital which yields no annual interest, but once turned to light, to heat, and force is gone for ever into space." In Shropshire the workings have passed away from the exhausted western side of the field to group themselves along the eastern in Staffordshire the famous Dudley seam will in a few years be as a tale that is told ; in the great Northern coalfield almost every available "royalty" is taken up, large tracts have been cleared out, and already progress is made in leaving terra firma and working out under the North Sea.

It must then be understood that the rapid exhaustion of certain districts, and the calculation of what coal remains, are not the speculations of theorists, but the fair deductions from weights and measures ascertained with a great amount of practical care and discrimination.

Reference need not be made to the older estimates of the duration of our coalfields, as the present enormous output did not enter into the calculations of the earlier writers, nor were they provided with the requisite data for reasonable approximations. It was only in the classical coalfield of Durham and Northumberland, that the position and character of the seams were so well known to the viewers as to admit, many years ago, of approach to accuracy.

Mr. Greenwell, a colliery viewer, thoroughly acquainted with the district, taking the quantity producible from each seam, including that which lies below the Magnesian Limestone, as well as a width of two miles under the sea, calculated in 1846 that 331 years would, at the then existing rate, exhaust the whole area. At that time only 10,000,000 tons per annum of round coal were raised. In 1854, when the amount had reached 14,000,000, and a larger proportion of small coal became available, Mr. T. Y. Hall, also a member of the Northern Institute of Mining Engineers, estimated the duration at 365 years, but stated that it would be reduced to 256 years if the demand were to increase to 20,000,000. And now since the output in 1891 reached 185,373,445 tons, and there is reason to expect a still further increase of production, it is obvious that the time thus estimated must be greatly abbreviated, and that Sir William Armstrong, in calling attention to the rapid exhaustion of coal, in his address at Newcastle in 1863, based his argument on no unsound foundation.

As will be seen from the foregoing statistics, the quantity of coal raised in Great Britain in 1854 has been nearly trebled in 1891, yet that fact will hardly justify the expectation that the consumption in the future will continue to increase in a like ratio. We are rather led to think that the increase of our production from 2,000,000 to 3,000,000 of tons annually, serious as it undoubtedly is, will keep us within comparatively moderate figures for some time to come, and at all events defer, as regards the country at large, the evil day for two or three centuries.