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- The Sauwartan Pit-Head Frame and the Midi Fault

The Sauwartan Pit-Head Frame
Sauwartan colliery is a fascinating testament to Wallonia’s industrial heritage. The Société du Bois de Saint-Ghislain, which owns the site, was founded in 1791 and played a major role in the region’s coal mining history.
However, as European technology advanced, there was less demand for coal, and the company ceased operations by 1938. Today, Sauwartan is home to the only remaining concrete pit-head frame in the Borinage.
Typical of the architecture of the time, it was built in 1928 to replace a wooden structure. In Belgium, pit-head frames are nicknamed “belle-fleur” (beautiful flower). Designed by the French engineer Freycinet, it is built from reinforced concrete. The top of the frame supports the pit head machinery over which the extraction cables pass. This imposing structure was built using concrete beams filled with bricks. Concrete was used because it is quick to make and flexible in design – essential considerations for industrial operation. The rest of the colliery facilities now lie in ruins, overgrown with vegetation, including the mound of the slag heap which has been reclaimed by nature. Nowadays, slag heaps are of major interest to biologists, and this example is home to amphibians and bats. It is part of the Natura 2000 network of European protected areas.
The Sauwartan Pit-Head Frame was officially classed as a monument and heritage site on 30 August 1991 and currently sits on private land.
The Midi Fault
A fault is a geological phenomenon, referring to a break in the Earth’s crust. The thrust fault (or overthrust fault) results from compression that causes one rock compartment to slide over another. They can vary in length from a few metres to several hundred kilometres.
The Faille du Midi can be seen in the Bois de Colfontaine in the Carrière du Cerisier quarry. At this site, you can see the Ardennes Allochthon overlapping on the Brabant Parautochthon and different tectonic scales. This situation is the result of the formation of the Variscan mountain range about 300 million years ago. Carboniferous schist, dating from about 330 million years ago, is covered by Devonian sandstone that is about 415 million years old. This geological makeup is typical of the Belgian part of the Nord-Pas-de-Calais mining basin. In some places, carboniferous limestone dating back around 340 million years is pinched against the Midi Fault, as at the Cerisier quarry, where it was mined in the 18th century.
Not far from the Sauwartan slag heap, on the banks of the River Elwasmes, you can see the Midi Fault – a geological phenomenon which runs across Belgium.