NPP Klonk - hranice silur-devon EarthCache

CZ: Lehce dostupna earthcache celosvetoveho vyznamu (viz listing). Na souradnicich najdete pamatnik a informacni tabuli. Ve vzdalenosti 370 metru pak na severovychode vidite NPP Klonk s oznacenou hranici silur - devon. Na samotnou NPP Klonk je vstup zakazan.

EN: Easy accessible earthcache with worldwide meaning (see listing). On earthcache coordinates you can find monument and information table. And from here you can see at 370m to the northeast the NPP Klonk with silurian-devonian boundary.

CZ: Narodni prirodni pamatka Klonk

Klonk ma svetovy stratigraficky vyznam, nachazi se zde hranice mezi dvema prvohornimi utvary, silurem a devonem. Rozklada se na plose 8,9 ha v nadmorske vysce 322 az 418 metru. Lezi na katastralnim uzemi obce Suchomasty. Byla vyhlasena v roce 1977.

Severne od Suchomast se nad Suchomastskym potokem nachazi prikry sraz zvany Klonk. Buduji ho vrstvy svrchniho siluru a spodniho devonu. Pravou, jizni cast vychozu tvori tufiticke bridlice a vapence kopaninskeho souvrstvi. Stratigraficky vyznamna je vsak leva, severnejsi cast, kde vystupuje pozarske souvrstvi nejvyssiho siluru a spodni polohy lochkovskeho souvrstvi nejnizsiho devonu. Nejvyssi silur i spodni devon je zde shodne litologicky vyvinut jako tmave sede, vetsinou jemnozrnne deskovite vapence, stridajici se rytmicky s vlozkami vapnitych bridlic. V hranicnim intervalu neni zadna facialni zmena a profil tvori jediny kontinuitni sled.

Vlastni hranice (viz foto v listingu nebo na informacni tabuli a velkou znacku na skale) mezi silurem a devonem je vedena podle nastupu vudciho graptolita Monograptus uniformis, ktery tvori ve svetovem meritku nejnizsi devonskou graptolitovou zónu. Graptoliti jsou zde provazeni dalsimi stratigraficky vyznamnymi skupinami zivocichu, jejichz spolecny vyskyt zarucuje vzajemnou kontrolu stratigrafickych dat i siroke mezinarodni srovnani. Jsou to zejmena trilobiti, z nichz bazi devonu charakterizuje vyskyt druhu Warburgella rugulosa. Z dalsich vudcich zkamenelin jsou zde konodonti druhu Icriodus woschmidti a Angochitina chlupaci. Vudci druhy provazi cetna dalsi fauna, jako lodenkoviti, graptoliti, trilobiti, mlzi, plzi, ramenonozci, fylokaridni korysi aj. Vzacne zde byly nalezeny i zbytky suchozemske flóry. Sled hranicnich vrstev je na Klonku odkryt bez jakehokoliv negativniho tektonickeho poruseni. Jednotlive vrstvy jsou v odkryvu cislovany, vlastni hranice mezi silurem a devonem probiha uvnitr vrstvy c. 20.

Klonk byl vybran za stratotyp hranice silur - devon po siroke mezinarodni diskusi a mnoha reviznich cestach po svetovych silursko - devonskych oblastech. Konecne rozhodnuti o volbe stratotypu bylo prijato Mezinarodni stratigrafickou komisi na zasedani 24. mezinarodniho geologickeho kongresu v Montrealu roku 1972. Klonk je prvnim stratotypem hranice mezi geologickymi utvary, ktery byl prijat podle novych exaktnich zasad stratigraficke klasifikace.

Prikry sraz Klonk u Suchomast je jako svetove vyznamny geologicky odkryv chranen. Roku 1977 byl vyhlasen jako chraneny prirodni vytvor (dnes narodni prirodni pamatka). Pod Klonkem byl roku 1977 zrizen pamatnik, ktery symbolizuje dve geologicke vrstvy spjate mezinarodnim usnesenim. Pamatnik je dilem akademickeho sochare Jiriho Novotneho, je vyroben ze zbuzanskeho mramoru (dvorecko - prokopske vapence), vazi 6 tun a je vubec prvnim pamatnikem sveho druhu.
(www.otevrena-veda.cz)

EN: National natural monument Klonk

The Klonk NNM is of worldwide stratigraphical importance, as it lies on the border between two older Palaeozoic formations – the Silurian and the Devonian.

The national nature monument lies in the parish of Suchomasty in the Ceský kras – Bohemian Karst and in the Stredoceský kraj – Central Bohemian region. The monument was declared in 1977 and covers an area of 8.9ha and lies at elevations of 322-418 metres above sea level.

The steep slope known as Klonk lies to the north of the village of Suchomasty and above the Suchomastský potok Stream and is built of layers of limestones from the Upper Silurian and Lower Devonian periods. The right-hand (southern) part of the outcrop is built of tuffite shales and limestones of the Kopanina formations. However, the left-hand (northern) part of the outcrop is of stratigraphic importance. Here the Požáry Formation from the uppermost Silurian and the lower positions of the Lochkov Formation from the lowest Devonian are exposed. The highest Silurian and lowest Devonian are both developed lithologically here as dark-grey and mostly fine-grained block limestones, which are interbedded rhythmically with bodies of calcareous shales. There is no change in appearance and the profile forms a continual sequence.

The border between the Silurian and the Devonian (see photo in listing or on information table and big sign on the rock) is defined by the increasing numbers of the dominant graptolite Monograptus uniformis, which is regarded as the lowest Devonian graptolite zone on a world-wide scale. Here the graptolites are accompanied by other stratigraphically significant animal groups. When the graptolites and other fossilized animals occur together, this enables mutual controls of the stratigraphic data and wider international comparisons to be carried out. These fossils include trilobites such as Warburgella rugulosa, which is a characteristic species for the base of the Devonian. The conodonts Icriodus woschmidti and Angochitina chlupca are also dominant fossils which can be found at Klonk. These dominant species are accompanied by numerous other fauna types, such as nautilids, graptolites, trilobites, molluscs, gastropods, brachiopods, phyllocarid crustaceans etc. Remnants of terrestrial flora have also been found here. The sequence of border strata is exposed on the Klonk slope without any negative tectonic disturbance. The individual layers in the exposure profile are numbered. The actual border between the Silurian and the Devonian takes place inside layer # 20.

Klonk was chosen as a stratotype of the Silurian–Devonian border after wide international discussion and many assessment trips to Silurian-Devonian regions around the world. The final decision to recognize Klonk as a stratotype was made by the World Stratigraphic Commission at the 24th International Geological Congress in Montreal in 1972. Klonk was the first stratotype of a border between geological formations, which was accepted according to the stricter new rules of stratigraphic classification.

The steep slope of Klonk is protected as a geological site of world importance. The locality was declared a protected natural formation in 1977, and is now a national nature monument. A monument which symbolizes two geological strata, was erected at Klonk in 1977 to commemorate the international declaration. The memorial is by the sculptor Jirí Novotný, is made of Zbuzany marble (Dvorecko-Prokopský limestone), weighs 6 tonnes and was the first geological monument in the world.