The Northern Harz Boundary Fault ( or ''Harznordrandverwerfung'') is a geological fault where the Harz Block, which consists of rocks formed during the

Palaeozoic The Paleozoic ( , , ; or Palaeozoic) Era is the first of three geological eras of the Phanerozoic Eon. Beginning 538.8 million years ago (Ma), it succeeds the Neoproterozoic (the last era of the Proterozoic Eon) and ends 251.9 Ma at the start of ...

Era and folded in the course of Hercynian mountain building, borders on the Subhercynian Basin or Harz Foreland. The fault is also known in English as the Harz North Rim Fault or Harznordrand Thrust (Fault).Nielsen, Ole (2008). ''Salt tectonics'' a
my.opera,com
Accessed on 28 Nov 2010. The northern edge of the Harz is oriented in a Hercynian (WNW-ESE) direction and runs from Neuekrug- Hahausen via

Langelsheim Langelsheim () is a town in the Goslar (district), district of Goslar in Lower Saxony, Germany. Geography The municipality is situated between the river Innerste and its tributary the river Grane (river), Grane, on the northern edge of the Harz ...

Goslar Goslar (; Eastphalian dialect, Eastphalian: ''Goslär'') is a historic town in Lower Saxony, Germany. It is the administrative centre of the Goslar (district), district of Goslar and is located on the northwestern wikt:slope, slopes of the Harz ...

Bad Harzburg Bad Harzburg (; Eastphalian dialect, Eastphalian: ''Bad Harzborch'') is a spa town in central Germany, in the Goslar (district), Goslar district of Lower Saxony. It lies on the northern edge of the Harz mountains and is a recognised saltwater spa ...

, Ilsenburg,

Wernigerode Wernigerode () is a town in the Harz (district), district of Harz, Saxony-Anhalt, Germany. Until 2007, it was the capital of the Wernigerode (district), district of Wernigerode. Its population was 32,181 in 2020. Wernigerode is located southwes ...

, Blankenburg,

Thale Thale () is a town in the Harz (district), Harz district in Saxony-Anhalt in central Germany. Located at the steep northeastern rim of the Harz mountain range, it is known for the scenic Bode Gorge stretching above the town centre. Geography The ...

and

Gernrode Gernrode () is a historic town and former municipality in the Harz (district), Harz District, in Saxony-Anhalt, Germany. Since 1 January 2014, it has been part of Quedlinburg.Ballenstedt Ballenstedt is a town in the Harz district, in the German state of Saxony-Anhalt. Geography It is situated at the northern rim of the Harz mountain range, about 10 km (6 mi) southeast of Quedlinburg. The municipal area comprises the vi ...

. The Northern Harz Boundary Fault forms the southern border of the Northeast German Basin, a part of the Central European Basin. The Subhercynian Basin, also known as the Harz Foreland, is a small sub-basin of the Northeast German Basin. This intracontinental basin that has been subsided since the

Permian The Permian ( ) is a geologic period and System (stratigraphy), stratigraphic system which spans 47 million years, from the end of the Carboniferous Period million years ago (Mya), to the beginning of the Triassic Period 251.902 Mya. It is the s ...

period was formed from the Hercynian foreland basins and accumulated sediments of the Mesozoic era. The basin was formed by a deformation or bulging of the Moho. In the Cretaceous the basin was squeezed by

Alpine orogeny The Alpine orogeny, sometimes referred to as the Alpide orogeny, is an orogenic phase in the Late Mesozoic and the current Cenozoic which has formed the mountain ranges of the Alpide belt. Cause The Alpine orogeny was caused by the African c ...

which also uplifted the Harz Block. The Northern Harz Boundary Fault was activated in the

Early Cretaceous The Early Cretaceous (geochronology, geochronological name) or the Lower Cretaceous (chronostratigraphy, chronostratigraphic name) is the earlier or lower of the two major divisions of the Cretaceous. It is usually considered to stretch from 143.1 ...

and the Harz was uplifted along the line of the fault. The Harz Block was thrust over the Mesozoic strata of the Subhercynian Basin, steeply tilting its

Mesozoic The Mesozoic Era is the Era (geology), era of Earth's Geologic time scale, geological history, lasting from about , comprising the Triassic, Jurassic and Cretaceous Period (geology), Periods. It is characterized by the dominance of archosaurian r ...

strata. The most intensive phase of uplift occurred in a period of about 2 million years from the middle of the

Santonian The Santonian is an age in the geologic timescale or a chronostratigraphic stage. It is a subdivision of the Late Cretaceous Epoch or Upper Cretaceous Series. It spans the time between 86.3 ± 0.7 mya ( million years ago) and 83.6 ± 0.7 m ...

age to the lower

Campanian The Campanian is the fifth of six ages of the Late Cretaceous epoch on the geologic timescale of the International Commission on Stratigraphy (ICS). In chronostratigraphy, it is the fifth of six stages in the Upper Cretaceous Series. Campa ...

. The completion of uplift is shown by the fact that the rocks of the

Upper Cretaceous The Late Cretaceous (100.5–66 Ma) is the more recent of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''cret ...

lie at a much shallower angle than those of the Lower Cretaceous, and that, in some places, they overlap discordantly. The uplift is still going on today. Along the western part of the fault, the Harz was lifted by at least 5 to 7 km, which can be estimated from the thickness of the

rocks deposited in the Harz Foreland and

eroded Erosion is the action of surface processes (such as water flow or wind) that removes soil, rock, or dissolved material from one location on the Earth's crust and then transports it to another location where it is deposited. Erosion is disti ...

Paleozoic rocks. The Harz was partly thrust over the layers of Mesozoic rock to the north. Here, the Mesozoic strata were tilted steeply (70-80 degrees) or even overturned. A good example is at the Langenberg Quarry, but there are also many other outcrops that show the steeply sloping strata. In these strata, rocks of the

Jurassic The Jurassic ( ) is a Geological period, geologic period and System (stratigraphy), stratigraphic system that spanned from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period, approximately 143.1 Mya. ...

are steeply inclined. Near Blankenburg and Ballenstedt there are rocks lying at steep angles from the

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 143.1 to 66 mya (unit), million years ago (Mya). It is the third and final period of the Mesozoic Era (geology), Era, as well as the longest. At around 77.1 million years, it is the ...

, which form the so-called Devil's Wall or '' Teufelsmauer''. They include, ''inter alia'', rocks of Heidelberg Sandstone, a

silicified In geology, silicification is a process in which silica-rich fluids seep into the voids of Earth materials, e.g., rocks, wood, bones, shells, and replace the original materials with silica (SiO2). Silica is a naturally existing and abundant com ...

quartz sandstone. Springs rise along the entire fault system, both those with low quantities of minerals as well as

mineral water Mineral water is water from a mineral spring that contains various minerals, such as salts and sulfur compounds. It is usually still, but may be sparkling ( carbonated/ effervescent). Traditionally, mineral waters were used or consumed at t ...

springs. The mineral waters are used, for example, in Bad Harzburg, by the spa industry.

References

Sources

* * {{coord missing, Lower Saxony Geology of Germany Tectonics Harz Regions of Lower Saxony

See also

References

Sources