The Classic Square Mile of Geology

The Harz consists of rather old rocks which are heavily alterated and faulted by old orogenies. Then there are numerous important deposits of valuable ores, which show different origins. And this in a rather boring hinterland of young, horizontal Triassic and very young glacial sediments. This made the Harz a predestined target for intensive and fruitful geologic work.

On his Harz journey, in 1784, Johann Wolfgang von Goethe called the Harz around Goslar the "klassische oder goldene Quadratmeile der Geologie" (classic or golden square mile of geology). He talked about a quadratic area with 7,5km width and height, and Goslar at the northern edge. 7,5km are a Prussian Mile.

The Harz has an extraordinary versatility of its geology on a rather small area. From the Silurian slates to the upside down lacustrine limestones from the Trias, spectacular plutonites like the Brocken massif and metamorphic rock, pillow lava and various ore deposits. Several geologic terms were named after local specialties. The term hercynisch is derived from the Latin form of the name Harz. The greywacke, originally Grauwacke is a term used by the local miners for worthless rocks, derived from the grey colour and pudding like structure (wacke). The ultramaffic rock Harzburgit was named after its locus typicus Bad Harzburg at the northern rim of the Harz, near Goslar.