Geology
Geologically, the Westerwald is part of the Rheinisches Schiefergebirge, and likewise represents a heavily eroded remnant of a great Variscan mountain system which in the Mesozoic characterized a great deal of Europe.
The Devonian bedrock is covered by volcanic masses from the Neogene, particularly basalt and tuffs. Economically important, besides slate, limestone and clay quarrying, were, and still are, iron and its processing industry between Rheintal (Unkel, Linz) and the lower Wied, pumice gravel in the Neuwied Basin, various mineral springs and, at one time, brown coal mining.
The whole Westerwald region lay under a tropically warm arm of the sea in the Palaeozoic (600 to 270 million years ago). This sea deposited layers of sediments many kilometres thick into the Variscan geosyncline, which were heavily folded in the orogeny that followed. The towns of Siegen and Koblenz on the Westerwald’s north and southwest edges even gave two Lower Devonian layers, with their colourful slates, their names. The upper mountain layers are formed of volcanic strata made of basalt containing tuffs.
In a few areas, slate and clay have long been quarried, the latter notably in the so-called Kannenbäckerland, but also in a few other places where the clay is worked into the salt-glazed grey Westerwald Pottery with cobalt blue decoration. The pottery industry is centred around Höhr-Grenzhausen. Exports, particularly to Italy, are also important (more than one million metric tons each year). In the mid 16th century, potters from Raeren in Belgium migrated into the Westerwald, bringing with them some of their moulds. This type of pottery was taken to the New World and was found in the early Chesapeake settlements. Today one finds not only highly crafted moulded vases and mugs but also a range of handcrafted utility ware, with hand-painted swirling floral motifs.
In the eastern Westerwald (the part lying in Hesse) are found interesting limestone deposits from the most varied of geological times. Erdbach limestone from the Lower Carboniferous gave one small time period the name “Erdbachian”.
Near Breitscheid are found the remnants of an atoll from the subtropical Devonian sea that was here 380,000,000 years ago. Parts of this limestone formation are worked in open-pit mining; near Enspel, a “fossil conservation area” has been instituted, in which institutes from several colleges conduct research and excursions. A few karst caves are of interest to speleology and bring about the temporary disappearance and reappearance of the Erdbach.
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