Bakony Mountains
(Transdanubian Central Mountains, Veszprém)
| Geographical setting: | The Bakony Mountains form, together with the Vértes, Gerecse (link coming up), Budai and Pilis, and Visegrád mountains, the upland region of Dunántúl or Transdanubia, also know as the Transdanubian Mid-Mountains or Central Mountains. The lowish range, rising to a maximum of 700 m asl., is situated in Western Hungary, wedged between Lake Balaton in the Southeast and the Little Hungarian Plain in the Northwest. The whole range is an enormous synclinal structure with the central axis following more or less the northwestern edge of the uplands. The rocks in the region consist mostly of Mesozoic limestones and dolomite with some Tertiary sediments filling the basins between. From a lithic point of view, the most interesting formations are of Middle Jurassic age which were formed within the large Tethys ocean as these contain locally large amounts of radiolarite or radiolarian cherts. |
| Similarities and differences: |
Within the Bakony Mountains three major types of radiolarite have been distinguished: Szentgál, Urkut-Eplény and Hárskút, as well as the radiolarian chert from Sümeg. Of these, the Szentgál-type is without a doubt the most typical having a (predominantly) livid red colour and typical white "desilification-spots", present in most fragments. The Urkut-Eplény-type is characterized by its yellowish to mustard yellow colour and the Hárskút variety is typically homogenous dark brown to black. These varieties are named after the localities where they are to be predominantly found. The whole problem, however, is that different types of radiolarites can be found at different outcrops and that the differentiation on micropaleontological inclusions and chemical composition seems quite impossible. The differences among the stones from the same source seem to be greater than between the different outcrops. Even in the very limited samples in our collection, there are brownish specimens from Szentgál, reddish material from Hárskút, and at Bakonycsernye we collected radiolarites with the whole spectrum of colours from yellowish, through red and brown to black. All radiolarites are fine grained, opaque, and have a silky luster on the mostly conchoidal fracture, but finding material that is internally flawless is quite hard as most samples, even of the Szentgál-type, are heavily fractured. The only raw material readily separated from the rest are the (Lower Cretaceous) radiolarian cherts from southwestern part of the Bakony Mountains around Sümeg. They are typically light gray to brownish gray and slightly translucent. If differentiating and sourcing of the different materials within the Bakony Mountains is already fraught with difficulties, the situation really gets complicated when other regions are included. As most radiolarites were formed in deep-sea sediments of the Jurassic Tethys Ocean, they can be found in a wide zone ranging from the Italian Alps well into the Himalayas. In Central Europe alone, sources of radiolarite can be found in the Spanish Cordillera, the Alps in Switzerland, Italy and Austria (e.g. Antonshöhe), in the Carpathians in the Slovak Republic (e.g. Vlára Pass and Čergov Mountains, links coming up) and Southern Poland (e.g. Podhale Basin and Pieniny Mountains) as well as in Romania and Serbia. As they were mostly formed in similar environments in the same geological macro-region during the Jurassic, it will be very hard, if not impossible to differentiate all sources. Some work has been done (see for example Biró 1986a), but it will take a major effort from scientists from the whole Carpathian/Alpine region to achieve useful results. For the radiolarites from the Transdanubian Central Mountains it might be possible to separate them from other Carpathian sources on the ground that they are somewhat older (Middle Jurassic, Bathonian/Callovian) than those to the North and South, as these were formed during the Upper Jurassic. Another line of research that might be followed are microfacial investigation like described in Affolter 1999, with which that author has great succes in differentiating flint sources in the Southern and Western Alps (e. g. Affolter 2000 and Affolter, Sedlmeier & Zurbuchen 1997). |
| Extractability and use: | Within the Bakony Mountains four mining sites are known at Sümeg-Mogyorósdomb, Szentgál-Tüzköveshegy, Bakonycsernye-Tüzkövesarok and Hárskút-Édesvízmajor, of which two have been partly excavated (Sümeg and Szentgál). In all cases the silicious material seems to have been mined from primary deposits in Mesozoic limestones. On the excavated sites exploitation took place in wide open pits on a very large scale. On all extraction sites mining implements in the form of hammerstones and antler picks have bee found. These find prove, even without extensive archaeological excavation, the exploited sources to be mining sites, more than can be said of quite a lot of so-called prehistoric mines in other parts of Central Europe, notably Germany. Especially at Szentgál the scale of the prehistoric exploitation seems to have been huge, meriting the description as a "prehistoric industrial site". It is to be expected, that other extraction sites or even mines are to be found in the region, particularly for material of the Urkut-Eplény-type, which has been popular during long times in Prehistory (see below). Due to the occurrence of the radiolarites in narrow banks and the frequent internal fracturing, most tools are made on flakes and shortish blades. Most artefact retain some of the surrounding parent rock or cortex, notably those made on the Szentgál-type material. Some experimental knapping showed it was a lot easier this way to make elongated flakes, instead of shattering your carefully prepared core. |
| Prehistoric distribution: | About the distribution of the different materials outside Hungary is not much known, although detailed studies within the country give a clear, albeit sometimes strange, picture. Within Hungary, the circulation of all types of radiolarite and chert from the Bakony Mountains is mostly confined to Transdanubia, that is, the materials hardly cross the Danube into the Great Hungarian Plain. This seems to be caused by the extensive use of Carpathian obsidian and several kinds of limnic quartzite in this area. A exception to this pattern is a narrow strip directly to the East of the Danube, roughly between Budapest and Baja in Southern Hungary, which geographically belongs to the Great Hungarian Plain, but is archaeologically linked more with Transdanubia. Towards the Northwest the Szentgál- and Urkut-Eplény-types have a fairly wide distribution, although little systematic mapping has been done. Finds of these kinds of material are reported from Austria, the Czech Republic and occasionally Southern Germany, over 600 kilometers from their sources. The radiolarian chert of the Sümeg-type has the strangest distribution we ever saw: although the mines are quite extensive, the material seems to have circulated in a very limited area immediately around and a bit to the Southwest of the extraction site. |
| Last modified on: January 12, 2002 |
Contents primarily by: Rengert Elburg |
Comments to: |