NO-SERVICE INFORMATION STAND (BIS)
GPS: 49°53’53.76″ N, 15°56’46.85″ E
The open-air information system for the visitors of the Iron Mountains and for geotourists in the territory of the Iron Mountains PLA and the Iron Mountains National Geopark is structured into several levels. No-service information stands (BIS) are ranked among essential elements of this system. The choice of the site for BIS location is not an arbitrary one: the site must always meet many criteria representing one of the five themes contained in the logo of the “The Iron Mountains – a geologically significant regionˮ project and the Iron Mountains Geopark.
THE VILLAGE OF PODLAŽICE NEAR CHRAST HAS BEEN CHOSEN FOR THE NO-SERVICE INFORMATION STAND FOCUSED ON HYDROGEOLOGY.
The site is located on the southern margin of the Bohemian Cretaceous Basin. The basin fill is represented by sediments of Cenomanian (Peruc-Korycany Formation) to Lower Turonian age (Bílá hora Formation). They include quartzose sandstones with glauconite and rich marine fauna, 30–50 m in thickness. These are overlain by calcareous and sandy siltstones (opokas), forming a continuous succession 30–40 m thick.
Upper Cretaceous sediments were subjected to intensive faulting and jointing, related with the uplift of the massif of the Iron Mountains in the Tertiary. Geological setting of the complexes of sandstones and spiculitic marlstones, together with their tectonic deformation, produced a hydrogeological structure known as the Podlažice Depression. The area of groundwater recharge, characterized by seepage of precipitation water, occupies a broad forested belt with sandstone and marlstone outcrops south of Podlažice. Specific features of this area include infiltration of surface waters from the banks and bottom of the Žejbro Stream into the rocks below. The combination of these two processes with the high pore permeability of sandstone and the excellent joint permeability of spiculitic marlstones renders migration of infiltrated water towards the north, down the dip of sandstone and marlstone strata. In the area between Chrašice, Rosice and Dobrkov in the north, the presence of clay-filled vertical joints and faults induces a rise in groundwater table and a discharge of groundwater to the surface.
The region of the Iron Mountains ranks among unique areas within the Czech Republic in terms of groundwater occurrences and groundwater reserves. Owing to favourable geological conditions, water from the mountains (from granite, gneiss and schist) infiltrates into Cretaceous sediments (sandstone, spiculitic marlstone) in the foothills. Withdrawal of water from these sediments is provided using wells, galleries and boreholes. The history of water-supply industry dates to the 17th century (Podlažice – Chrast). Sites like Nové Hrady, Skuteč, Choltice, Heřmanův Městec, Studenec or Blatnice are familiar to almost every hydrogeologist or water-supply expert.
Pilgrimage in quest of hydrogeology, or water, can be therefore best started at Podlažice – an almost cult place for the hydrogeologists and water-supply experts. Works conducted here in the mid-20th century marked a threshold for new generations of hydrogeologists. The yield of as much as 120 litres per second of potable water from six boreholes covers the consumption of 85,000 inhabitants.
The no-service information stand consists of a wooden structure with five panels generally expanding the theme of groundwater and surface water regimes on both foothills of the Iron Mountains. One of the panels also refers to closely accessible phenomena related to the occurrence of springs and significant withdrawal areas yielding potable water.
Blocks of rocks from the territory of the Iron Mountains are scattered around the wooden structure, totalling 8 accessible samples from 6 sites. They include sediments with pore permeability (gravel, sandstone), joint–pore permeability (sandstone, conglomerate) or joint permeability (opokas). The displayed samples also include rocks of the so-called hydrogeological massif, dominated exclusively by joint permeability.
The blocks are mostly polished, and always provided with an information pillar. The pillars comment on the origin and composition of the rocks, and bear colour photomicrographs.
Structured information provided in the no-service information stand allows the visitors (geotourists) of the Iron Mountains to get easily orientated and make their choice among other sites.