The story of coal is deeply rooted in the geological history of the Carboniferous period, which began around 345 million years ago and ended approximately 290 million years ago. During this time, the Durham coast was a vastly different landscape, hosting large rivers flowing towards the sea. These rivers terminated in shallow marine environments, giving rise to massive delta complexes.

The formation of coal measures involves a cyclical process of deposition. As sea levels fluctuated, the deltas experienced changes in water depth. During periods of rising sea levels, deep and quiet conditions prevailed, leading to the deposition of mud or shale. Conversely, when sea levels dropped, the rivers carried sand into the shallow coastal waters and onto the deltas, resulting in the deposition of sandstones.

Above the deltas, lush swampy environments developed, teeming with vegetation. The warm climate during the Carboniferous period contributed to the growth of luxuriant forests across the delta tops. As vegetation died and decayed, peat-like sediments began to form. Over time, the accumulation and compaction of these sediments led to the transformation of plant matter into coal.

The Coal Measures comprise repeated cycles of mud, sandstone, and coal layers, known as coal seams. The cyclicity in the deposition of these materials created the diverse strata seen in the region’s geology.

To extract the valuable coal seams, miners had to work below sea level, necessitating the sinking of shafts through the Permian limestone, extending beneath the North Sea. These extensive mine shafts, stretching several miles offshore, are a testament to the dedication and determination of the coal miners.

One prominent location along the Durham coast associated with coal mining is the Blast Beach, where Dawdon Colliery was established in 1907 and operated until 1991. The production of coal and the disposal of rock waste profoundly impacted the beach, leading to the mechanical dumping of rock waste onto its shores. This resulted in changes to the geomorphology and shape of the beach over several decades.

The fascinating geological history of coal and its extraction in the Durham region provides valuable insights into the Earth’s dynamic processes over millions of years. By understanding the formation and extraction of coal measures, we gain a deeper appreciation of the geological significance and environmental impact of this valuable resource.