site 38

Where is the site located?

GPS: 49°44’1.97″ N, 15°45’51.17″ E

The area lies in the southern extension of the Iron Mountains National Geopark. The Iron mountains are noted as a prominent forested line on the horizon, trending towards the Elbe River in the northwest. The base of the slope is lined by the winding Doubrava River within the Doubrava Basin. The whole scenery opens in front of us if we proceed to the very edge of the Štikov Quarry.

What is the geological position of the site?

The site is located in the Bohemian Massif, in the marginal area of the Central Bohemian Region, where metamorphosed Proterozoic rocks are exposed, mixed with magmatic rocks. Rocks at this site are silent witnesses of the strength of the past orogenic processes. The appearance of the present landscape was considerably affected by movements along a deep fracture in the Earth crust.

What happened at this site in the past?

– 550 million years

The end of the Proterozoic and the beginning of the Paleozoic is marked by a rearrangement of lithospheric plates, resulting in the Cadomian Orogeny. The original rocks, produced by marine sedimentation and submarine lava effusions, were subjected to metamorphism by high pressures and temperatures. A deep-reaching fracture originated in the Earth crust. Magmatic bodies were rising and later became progressively folded together with their host rock. This site was located on the edge of the continent of Gondwana on the Southern Hemisphere.

– 350–300 million years

At the end of the Paleozoic, the rocks were subjected to another orogenic process – Variscan Orogeny. Again, this process changed their material composition and induced compressional deformation. And again, hot magma was released from the depth of the Earth by the orogenic processes. Collisions of a number of drifting continents eventually produced the huge supercontinent of Pangea. This site was located approximately on the Equator.

– 25 million years

In the course of the Tertiary, this area was composed of hard metamorphic and magmatic rocks. These rocks were forming a flat, levelled elevation, covered with younger Mesozoic sediments deposited by the Late Cretaceous sea. This area became a part of the Eurasian Plate and reached the Northern Hemisphere. An unstable environment close to an old deep-seated fault resulted in dense jointing of the rocks and their fragmentation into separate blocks. The Alpine Orogeny in the southeastern part of Central Europe formed the Carpathians and the Alps and produced a compressive impulse which reactivated the movement of the crustal blocks. Mutual displacement of these blocks reached as much as several hundred metres within the next millions of years. Uplift of the northeastern block and its thrusting over younger Upper Cretaceous sediments created the background for the present staircase topography of the landscape. Sedimentary cover became soon eroded from topographically higher areas.

– 2 million years

The process of weathering and erosion, which affected the rocks in the Tertiary and Quaternary, was almost completed. The exposed rocks were worn down by wind and fractured by frost due to the alternation of glacial and interglacial periods. The landscape was shaped by streams.

What does the site display today?

Rocks around Štikov belong to the southern extension of the Železné hory plutonic complex. This site is located in its oldest part, called the Všeradov Zone of Cadomian origin. It comprises rocks generated from magma – that is, rocks allied to granites and their related diorites. Nevertheless, they were subjected to pressure and temperature changes (regional metamorphism) during later orogenic processes. This is why we call them metadiorites and metagranites. These rocks are dark grey to black, fine-grained, with hornblende (a dark mineral of the amphibole group) prevailing over quartz and feldspar (light minerals). Dominance of this mineral in some portions produces amphibolite – a durable metamorphic rock.

Further northwest, towards the Vestec area, the Iron Mountains are composed of host rocks of the Železné hory pluton, i.e. metamorphic rocks which were also affected by the emplacement of the magmatic body. Among others, they include migmatitized gneiss – a rock of two components, the gneiss one and the granite one, which are mixed together in various patterns.

On its southwestern slope, the crest of the Iron Mountains is lined by Mesozoic sedimentary rocks of Upper Cretaceous age: sand- and clay-dominated sediments left behind by the Late Cretaceous sea. Later, they were consolidated into claystone, marlstone and sandstone.
The character of the landscape was affected by a tectonic line (a fault) of regional signifikance, stretching between Týnec nad Labem and Krucemburk. It is called the Železné hory Fault and represents a segment of the so-called Elbe Lineament (a set of faults near the Elbe River) – an old, deep-reaching fracture in the Earth crust.

The steep southwestern slope of the Iron Mountains is a product of the so-called Saxonian tectonics, which was a response to the Alpine Orogeny. Blocks along the Železné hory Fault moved relative to each other. Hereat, the block of the Iron Mountains was uplifted by several hundred metres and thrust over younger, Upper Cretaceous sediments. These sediments were rapidly eroded from the uplifted northeastern block of the Iron Mountains, exposing the previously hidden deep magmatic bodies. In contrast, they have been preserved in the southwestern block beneath the slope of the Iron Mountains, forming the so-called Cretaceous of the Long Furrow filling the Doubrava Basin. These sediments were also segmented into separate blocks along faults transverse or oblique to the course of the main Železné hory Fault.

What was affected by man?

This is one of the sites realistically displaying the history of clashes of interest between the utilization of mineral wealth of the country on one hand, and environmental protection, conservation of the picturesque character of landscape and of the legacy of our ancestors on the other hand.

The forested line of the Iron Mountains is incised at one place east of Sloupno. This scar – a stone staircase visible from a distance – originated mainly between the 1960s and 1980s. At first, geological prospection was conducted to find material suitable for the production aggregate and building stone. A mineral deposit was explored, reserves of stone were calculated, and legal documents were finally elaborated to define the exclusive territory of the deposit and the mining area. The area then designated for mining includes wide surroundings of the quarry, the whole community of Štikov and also the memorable Štikov Linden. A part of the village buildings were really taken down to give space to stone quarrying. The stone staircase, formed by the individual levels of a strip mine, is now visible from a long distance.

What was discovered?

This site has been incorporated in the Iron Mountains Protected Landscape Area since 1991. Its status guarantees nature and landscape conservation at large. At the same time, self-governmental and civic initiatives have been established in the field of environmental protection. These organizations bring together people on the other side of the barricade. They strive at the definition of rules governing the conditions of mining. Their goal is to prevent the crushing of this picturesque part of the Iron Mountains into aggregate and to protect the Štikov Linden. In 2005, the Štikov Linden earned the title “Tree Hero” in the national contest “Tree of the Year” because it somewhat slowed down the pace of quarrying with its legal protection zone. From then on, certain willingness to compromising occurs on the side of the mining company. Let us hope that we will be still having the opportunity to enjoy the view of the Iron Mountains and the Doubrava River basin from the adapted and secured viewpoint on the edge of the quarry, in the shade of the ancient linden tree.

“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 Štikov community, not far from the memorable Štikov linden. The edge of the quarry lies some 100 m west of the information panel. The quarry is an active one, and any access is permitted only after a prior consent of the company operating the quarry.