Where is the site located?
GPS: 49° 42′ 50.12″ N, 15° 48′ 10.74″ E
The area lies in the southern extension of the Iron Mountains National Geopark, on southwestern slopes of the Iron Mountains which progressively descend to the Doubrava Basin with the winding Doubrava River. The close vicinity of a picturesque-positioned village provides important sources of groundwater, which were installed by our ancestors in perfect quality and which serve their purpose until these days.
What is the geological position of the site?
The site is located in the Bohemian Massif, in the southeastern part of the Bohemian Cretaceous Basin. The basin fill has been preserved along the whole southwestern margin of the Iron Mountains in a structure called “the Long Furrow Cretaceous”. Upper Cretaceous sediments were modelled by subsequent geological processes, creating a structure very favourable for the accumulation and utilization of groundwater.
What happened at this site in the past?
– 95 million years
In the course of the Mesozoic, the supercontinent of Pangea was falling apart into separate lithospheric plates, which drifted atop the elastic asthenosphere. In the latest Mesozoic, this area was lying on the Northern Hemisphere, becoming a part of the Eurasian Plate. The climate was very warm, controlled by the greenhouse effect which induced a rise of global sea level. Flooding occurred over large portions of dry land. In the Late Cretaceous (a part of the last period of the Mesozoic), this site was a shallow sea passage, progressively flooded by warm sea waters. It was located in a shallow near-shore zone, locally dominated by sand, abundantly colonized by bivalves, gastropods, crustaceans and fish. With prolonged flooding, progressive deepening of the depositional area occurred.
What does the site display today?
This site is built by sediments of Upper Cretaceous age, which constitute the extension of the Bohemian Cretaceous Basin elongated along the southwestern slope of the Iron Mountains in the form of the Cretaceous of the “Long Furrow”. They comprise formations of largely marine sediments, originally unconsolidated, which were subjected to diagenetic changes (hardening) through geological time.
The lowermost unit is the Peruc Member formed by conglomerate and claystone deposited in freshwater environments. It is followed by sandstone and claystone of marine origin, 6 to 25 m thick, pertaining to the Korycany Member. Both these units are of Cenomanian age (the first age of Upper Cretaceous). They are overlain by ca. 40 m thick succession of marlstone and sandy marlstone of the Bílá hora Formation, deposited in the Early Turonian (the oldest part of the second age of Upper Cretaceous). The Jizera Formation lies the closest to the earth surface and consists of harder silty marlstone with spongilitic admixture. It was deposited in Mid Turonian (the middle part of the second age of Upper Cretaceous).
The original almost horizontally lying formations left behind by Late Cretaceous sea were later affected by tectonic forces, which are responsible for their present position. The pile of sediments was divided into separate blocks, and mutual movements of these blocks occurred along faults. The largest displacement occurred at the Železné hory Fault, along which the block of the Iron Mountains was uplifted by several hundred metres.
Most of the sediments have been removed by erosion. The remaining strata are somewhat bent, forming an asymmetrical concave-upward structure limited by the Železné hory Fault against the Iron Mountains. Upper Cretaceous sediments in this area display favourable characteristics for the accumulation and transport of groundwater. The individual formations contain rocks with aquifer properties, more or less naturally separated from each other by rocks with sealing properties, almost impermeable for groundwater.
As such, they constitute a multi-aquifer hydraulic system. The lowermost aquifer A is bound to sandstones of Cenomanian age, followed by aquifer B formed in sandy siltstones of Lower Turonian age, and by the topmost aquifer C associated with silty marlstones of Middle Turonian age. Groundwater flow is strongly controlled by faults: each block of Upper Cretaceous sediments has an independent regime of groundwater circulation. The Horní Studenec Block has been defined in the Horní Studenec area. A certain proportion of groundwater in this block is introduced from the adjacent crystalline rocks along faults. Drainage of groundwater in this area was mediated primarily by strata-bound springs. Aquifers A and B are the principal drained aquifers.
What was affected by man?
As has been noted by our ancestors already, springs concentrate to many places along the whole southern limit of the Horní Studenec village. Different types of withdrawal objects were constructed in the first half of the 20th century. From a technical point of view, they include simple spring reservoirs at spring issues as well as longer withdrawal incisions, adits and galleries designed to collect water along a specific horizon in Upper Cretaceous strata. All these objects were constructed with a high degree of precision, mostly by the Chmelík Company. Each of these objects bears its name, like the Matura Spring, the Culek Spring, the Němec Spring, the Sušárna adit, the MNV adit (MNV was an abbreviation for a local government office), the Church adit or Adit I. Based on the results of a hydrogeological survey in the 1980s, these sources were boosted by drilled wells.
What was discovered?
Local sources yield high-quality groundwater meeting all criteria for potable water. These water-supply objects now enter a wider system supplying water for the Chotěboř area and a part of the Havlíčkův Brod area.
“The Iron Mountains – a geologically significant region” project of 2014
An information panel was manufactured within the project of “The Iron Mountains – a geologically significant region”. It was installed at the western limit of the Horní Studenec village, by the road between Horní Studenec and Podmoklany, some 100 m from the sign of the end of the village. Access to the withdrawal areas is permitted only when accompanied by the operating company staff.