For more than 60 miles from Leeds to Derby, coal deposits come to the surface and dip gently toward the east beneath layers of younger formation. The width of the exposed Carboniferous area narrows from 25 miles in the north to 10 miles in the south.
The industrial development based on coal differs in the various sections. In the north the famous wool industry of the West Riding of Yorkshire is concentrated around Leeds, Bradford, Huddersfield, and Halifax--the industrial focus of more than two million people. These cities nestle in the Aire Gap with the bare moors of the Pennines rising close above them both to the north and south. In this gap, during the early part of the last century, a canal was carried clear across England, connecting the Humber River and Hull on the east with the Mersey and Liverpool on the west. In some places it goes through tunnels. Its construction seemed justified because it connected two flourishing ports, passed through Leeds and what is still the world's greatest woolen manufacturing district, and was connected by a branch canal with a similar cotton-manufacturing district around Manchester. The canal never paid, however, because railroads soon superseded it, and its use is now limited.
Although most of the wool for these manufacturing cities is now imported, the presence of sheep in the Pennine Chain, together with coal and plenty of soft water, was the factor which induced a migration of the wool industry from Norwich to the West Riding. This greatest of wool-manufacturing sections is limited in area because soft water fit for manufacturing is restricted to the central part of the Pennine Chain where the millstone grit replaces the limestone. Here again a strong tendency toward specialization is observable; different communities are noted for special types of work. Bradford is the center for wool-combing and worsteds; Halifax for carpets and heavy woolen; Leeds, which is less essentially a wool city, specializes in wholesale clothing which occupies one fifth of the workers, but the making of machinery, locomotives, and factory equipment is also important.
Now, as in the past, the growth of the port of Hull on the Humber is intimately bound up with that of Leeds and Bradford. Unlike Newcastle, Hull is not self-sufficient. Without the manufacturing centers at the base of the Pennine Chain it would be merely the center of a small agricultural district and of a fishing industry less important than that of other places like Grimsby farther out to sea. But coal as well as manufactured goods from the Leeds-Bradford district and also from Sheffield, together with its own local industries, make Hull a great and flourishing city, famous for its progressiveness.
Sheffield, farther south, is an interesting example of a city which follows an inherited type of industry even though the original reasons for this have long since disappeared. Today, as for centuries, the name Sheffield stands for high-grade cutlery and other small steel goods. Yet, as Professor R. N. Rudmose Brown well says, tradition and social inheritance are practically the only discernible factors that now give Sheffield any advantage over other places on the coalfields of Britain as a steel manufacturing center. They are so strong, however, that they explain the curious anomaly of an inland town which manufactures many heavy goods from imported ore, and is a great center of ship-building materials although without access to the sea. Sheffield, like several other towns, got its start centuries ago through the smelting of local iron ore with charcoal from the surrounding forests. First the smelting furnaces were located on hills so that the winds might furnish a draft. Then they were moved to valley bottoms so that waterpower might be used for this purpose. Sheffield is located at the convergence of five upland streams on which 200 dams and waterwheels were once located. The local iron contains so much phosphorus, however, that the cutlery, trade began to depend on iron ore imported at great cost from Spain and Sweden through Hull. Then, in the eighteenth century the supply of wood was practically exhausted and it looked as if Sheffield would have to change its industries. But such conditions stimulated the British to invent methods of using coal as coke with which to smelt iron ore. Since Sheffield happens to be located on coalbeds, it still continues to manufacture iron goods, although neither the ore, the forest, nor the waterpower which originally fitted the site for this industry now has any importance.