Great Coal Formation

Coal, or 'black gold' as it became known, was literally the fuel of the Industrial Revolution. For much of the nineteenth century Britain led the world in the exploitation of its coal and iron ore deposits, along with those of tin, copper and lead, and it was largely self-sufficient in minerals until the end of the century. Within less than 200 years from the early decades of the nineteenth century, the industrialised western world burned up a significant proportion of the planet's reserves of solid organic fuel. Made essentially of plant remains that originally accumulated within ancient tropical rainforests, the coal measures took the best part of 18 million years of Earth Time (from 318.1 to 299 million years ago) to be laid down. Many but by no means all of the global coal deposits were laid down during what we now know as Carboniferous times. But in the early decades of the nineteenth century this fact was not generally appreciated, except by geologists such as William Smith. Huge amounts of private money were squandered and fortunes lost on fruitless searches for coal in strata of the wrong age.

In William Smith's day, the name Carboniferous was yet to be adopted by English geologists, although it was first formally used on the continent of Europe as early as 1808 by D'Omalius d'Halloy. For Smith there were the Coal Measures or Great Coal Formation, as it was also known, and below lay the Mountain

Limestone strata, which he was particularly familiar with from his work in the West Country around Bristol and the Forest of Dean.

The initial realisation of where coal was to be found depended largely on coal-bearing strata outcropping at the surface. The natural occurrence of such outcrops is relatively restricted, since many coal-bearing strata can easily be eroded and do not generally form prominent topographical features, except in a few places where the seams are thin and interlayered with much harder strata such as sandstones and limestones. In those situations exploitation of the coal is difficult, time consuming and costly. There are, however, some places where the coal measures are well exposed in coastal cliffs such as around Blyth on the North Sea coast of Northumberland, around Workington and the Solway Firth on the northwest coast, and to a lesser extent around Carmarthen Bay in South Wales.

The coals of Northern England and South Wales were first mined and used by the Romans. However, it was not until the ninth century that coals were again exploited on a regular basis in Northumberland. Monastic records show that by the twelfth century coal was regularly used as a fuel, and by the thirteenth century exported from Newcastle by ship to London and other major centres of population. The noxious and polluting properties of coal burning were first recognised as early as the thirteenth century, when for a time King Edward I imposed the death penalty for anyone found burning coal as a fuel.

As early as 1800, England was producing some 10 million tons of coal a year, and by 1847 production had tripled. In comparison France, despite extensive coal fields in the north of the country, was only producing five million tons by 1847. Coalmining continued to develop and expand in England, Wales and Scotland and rose fairly steadily until 1910. Then production peaked, with a total of nearly 300 million tons a year, and Britain was still the world's leading producer. There was a related rise in pig-iron production from 68,000 tons in 1788 to 1,347,000 tons in 1839. By contrast, China was producing well over a billion tons of coal in the mid-1990s.

From the point of view of the history of the Industrial Revolution, the most important coals were exposed in the steep valley side of the River Severn at a place called, appropriately enough, Coalbrookdale, near Ironbridge in the Welsh

Borderland county of Shropshire. Here, the combination of coal and sedimentary ironstone bands within the Coal Measures, along with limestone, water power and a navigable river with access to Bristol and the sea, produced one of the earliest centres of the Industrial Revolution. The first metal bridge in the world was made in 1779 at Ironbridge to span the Severn gorge. However, the Shropshire coal deposits turned out to be very restricted in their extent and it was not long before other, bigger coal fields began to be exploited. But this required new types of communication to transport the bulky and heavy coal to where it was most needed and new technology to follow the coal seams from the surface deeper and deeper underground.

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