The Arnika cave, located in the devonian limestones, is situated in the Propadle vody valley close to NW margin of the karst area called Czech Karst, 1km ENE of the monastery in the Svaty Jan pod Skalou Village. After heavy rain from 1st to 2nd of June 1995 it was observed, that a portion of the stream disappeared into the ground where it crossed a trail. Exploratory work in June 1995 were crowned successful. Inroads were made into the fissure area with a depth of 9 m. On June 14 salt was added to the water and after twenty hours it began to appear in Ivan and Ivanka springs in the monastery at Sv. Jan pod Skalou.
During work in from 2000 to 2004 speleologists managed to reach 32 m in depth. A special lift (Alvek) was installed to the cave to remove excess dirt.
Here you can see inside the cave -VIDEO 1.
During the speleologic activities, two profiles at the depths -11,10m and -15,10m were selected and studied by means of sedimentological and palaentological methods. While sediments of Profile , characterized as brown slightly sandy clay with irreegularly dispersed white and yellowish rounded quarz pebbles of 3cm in maximum and sharp-edged clasts of cherts (3cm in max), respectively brown, locally rusty-streaked silty clay in the uppe part, were paleontological sterile, unusual paleontological content was detecteed in the Profile 1. The sediment is characterised as calcareous brownish grey to grey silty clay with chaoticaly dispersed sharp-edged limestone clasts.
Vertebrate material is represented with poor fragments of several large mammals, of which a very small horse reminding Equus hydruntinus is of the particular interest as a possible glacial element among otherwise clearly Holocene taxa.
The Holocene malacofauna consist of mixed malacocoenoses composed of woodland, open ground and freshwater elements. The sample also includes a fragment of human cranium and one fragment of ceramic, probabbly asociated with Bronze Age Tresina Settlement.
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Jeskyne Arnika vznikla v udoli Propadle vody asi l km vsv. od kostela ve Svatem Janu pod Skalou v devonskych vapencich na krizeni podelneho a pricneho zlomu s vrstevnimi plochami. Po prudkem a vytrvalem lijáku z 1. na 2. cervna 1995 byly pozorovany napadne ztraty mensiho potucku pod povrch melke deprese c.111 v horní casti udoli Propadle vody v mistech, kde jej krizuje naucna stezka. Pruzkumné prace byly korunovany uspesnymi pruniky do puklinovitých prostor o hloubce 9 m. Dne 14.cervna byla kuchynskou soli obarvena vtekajici voda. Ta se po dvaceti hodinach zacala objevovat v klastere ve Svatem Janu pod Skalou ve vyverech Ivan a Ivanka.
Behem prolongacních prací v letech 2000-2004 byla jeskyne prohloubena na 32 metru pod vstup. Chodba vedouci na dno dostala nazev Rohovcová a jejím strmým prubehem je k Presypu vedena rucne pohánená lanovka. Odtud dále pres domek U svicky vede dalsi, jiz mechanizovaná draha na povrch. Takto je vyvazen natezeny materiál ven. V tomto období je objevena castecne volná prítoková Sucha chodba od závrtu 110. Spodni cast drahy je napojena na mechanizovany usek a tak ze dna Rohovcové chodby vyjizdí okov pohodlne na povrch pouhym stiskem tlacitka.
Jeskyni si prohlednete zde - VIDEO 2.
Behem speleologicke cinnosti byly vybrany a sedimentacne a paleontologicky prozkoumany dva profily. Paleontologicky sterilni sedimenty profilu 2 (v hloubce 15,1 m) vyplnuji zkrasovelou poruchu smeru VSV-ZJZ sirokou 30-40 cm. Jsou to hnede jily s nepravidelne rozptylenymi valounky kremene Dale jsou pritomny ostrohranne ulomky rohovce. Horni cast profilu tvori jil s naznaky horizontalniho zvrstveni a ojedinelymi uhliky velikosti do 1 cm. Sediment Profilu 1 (hloubka 11,1m) je tvoren jilem bez zvrstveni s chaoticky rozptylenymi vapencovymi kameny, s ojedinelymi bloky vapence do 30 cm velikosti a kameny rohovce dlouhe az 15 cm. V horni casti profilu lze ojedinele nalezt valounky kremene. Primarni vapnitost sedimentu umoznila zachovani fragmentu kosti; obratlovcu a mekkysich konchylii.
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