4.2 Coal distribution in the UK and Europe
The UK and Europe were fortunate in having extensive coalfields that powered the Industrial Revolution. Figure 33 shows the distribution of the major Carboniferous mires which became coal-bearing rocks across Europe, either outcropping at the surface or buried beneath younger rocks. The first thing that is evident from this map is that not all countries shared the same good fortune; either such rocks were deposited, but were subsequently eroded away, or they were never deposited in the first place.
In deciding which of these two possibilities is correct you need to look more closely at Figure 33. It shows the geography of Europe as it might have appeared in Late Carboniferous times, about 300 Ma ago, when the entire region lay close to the Equator. It is clear that the Carboniferous landmass bears little resemblance to the present-day coastlines, which are superimposed on the map for reference.
Why are the outlines of Greenland and Norway so close together in Figure 33?
The North Atlantic Ocean did not exist in Carboniferous times.
Carboniferous Britain and north Europe formed a low-lying plain backed by newly formed mountains to the south and a shallow sea to the north, beyond present-day Scandinavia. Tropical waterlogged mires developed across Britain and Ireland, through the southern North Sea into Belgium, the Netherlands and northern Germany and east into Poland, as well as between Greenland and Scandinavia. It is likely that coal formed across the whole of this area.
So, why aren't Carboniferous coal measures found over all the area that was land during that period? Consider the following.
Why are no Carboniferous coals found over the plains area marked in light green on Figure 33?
Although relatively low-lying, these areas (including Scandinavia, the Baltic States, south-eastern England and west Wales) were hilly enough to prevent the development of mires.
Why aren't Carboniferous coals preserved over all the area once covered by mires?
In many areas that have undergone uplift due to tectonic activity, erosion may have removed the coal-bearing sequence. (This happened in the Pennine area of the UK.)
Erosion also helps to expose Carboniferous coals by removing overlying, younger rocks. As a result, surface mining is common in the Ruhr area of Germany, in Poland, in the Midland Valley of Scotland, and in parts of Lancashire and Yorkshire.