THE „Kleiner Berg Hohburg“ NATURE RESERVE

The „Kleiner Berg Hohburg“ nature reserve, which has been protected since 1976, is located within the Hohburg Hills landscape conservation area. The geological foundation consists of a hilltop of Hohburg quartz porphyry, which rises 65 metres above its surroundings. Two habitat types worthy of protection have developed on these acidic rocks: the wood rush-beech forest and the Galium-oak-hornbeam forest. The Kleine Berg is a refuge for endangered animal and plant species such as the pug bat, the greater mouse-eared bat and the dormouse. The hill itself is also protected because of the geoscientifically significant glacial (Morlot rock) and wind (Naumann-Heim rock) striations. On the summit there are remains of stone and earth ramparts of a 9th century Slavic castle complex.

Glacial and wind striations on the Kleiner Berg – a national geotope

The Hohburg Hills belong to the Northwest Saxon volcanic complex. The porphyry was formed by violent volcanic eruptions during the Permian about 290 million years ago. Between 100 and 20 million years ago, during the warm, humid climate of the Upper Cretaceous and the Tertiary, intense weathering of the porphyry produced kaolin („china clay“). Today, the resistant rock form the hilltops of the hilly landscape around Hohburg. During the Elster and Saale ice ages – from about 400,000 years ago – huge inland ice glaciers advancing from Scandinavia abraded the mountains giving them their typical whaleback-like shape (drumlins). The porphyry peaks were left with elongated scratches and mirror-like surfaces. The geologist Carl Friedrich Naumann found these in the Hohburg Mountains as early as 1844 and interpreted them as glacial striations. This was long before the inland ice theory was generally accepted in the second half of the 19th century. He remarked: „Should the Nordic glaciers really have reached from the Scandinavian Mountains to the Wurzen Hills? I shiver at the thought.“ (B. v. Cotta, geologist, 1844).

Traces of the most recent cold period in Central Europe, the Weichselian period between 115,000 and 12,000 years ago, can also be found in the Hohburg Hills. Although the inland glaciers only reached as far as the present-day Berlin area, strong winds transported clay and sand particles from the low-vegetation cold desert (tundra) in the foreland of the glaciers onto the porphyry rocks with the effect of a natural sandblaster. Steady winds worked distinct groove structures into the Naumann-Heim rocks over thousands of years.

Captions and Legend

1. Summit area of the Kleiner Berg with position and direction of the glacial and wind striations (after Eissmann 1994).
2. Quartz porphyry abraded by the movement of the glacial ice in the area of the Morlot rock.
3. Wind striations from the Weichselian glaciation on the Naumann-Heim rock.

Hohburg quartz porphyry
Pyroxene quartz porphyry
Pyroxene granite porphyry
direction of the striations