Kautliku pank / cliff EarthCache

Kautliku pank on Saare maakonna põhjaranniku pankadest väikseim. Maksimaalne kõrgus keskosas ulatub 2,5 meetrini. Tänapäevalgi jääb pangajärsak laine aktiivse murrutuse vööndisse ning panga nägu uueneb aja jooksul järjepidevalt. Kogu pangajärsaku ulatuses paljanduvad pudedad Jaani lademe Paramaja kihistiku dolomiitsed mergelid - domeriidid. Jaani lademe domeriidid on siin nii savikad ja sinakashallid, et tunduvad pigem juba savikivimina. Kohati on kivim väga püriidikirjaline ning hoolika otsimise peale leiab panga seinast ka väikesi püriidi (kassikulla) pesakesi. Kautliku pank on üks väheseid domeriidipankadest, kus puuduvad põhjaranniku pankadele iseloomulikud plaatjad biohermsed dolokivid läbilõike ülemises osas, domeriiitidel lasuvad siin otse rannakruusad ja veerised. Seetõttu on pank ka loodusjõududele vähem vastupidav. Kautliku panga seinas paljanduvates kivimites leitud fossiilide järgi arvatakse, et sellised kivimid tekkisid vaikseveelise settekeskkonna ja avatud šelfi piiril. Kõige sügavamaveelised tingimused Jaani eal seostuvad vulkaanilise tuha vahekihtide esinemisega. See näitab, et Paleobalti mere telgnõo vajumine ja savimaterjali sissekande suurenemine olid seotud vulkaanilise aktiivsusega.

Küsimused:

1. Mis on mergel ja mis on domeriit? Kirjelda. (infotahvel)
2. Mis kontinendile kuulus Eesti Siluri ajastul? (infotahvel) 
3. Kui pikk on Sinu hinnangul pankrannik?
4. Kirjelda fossiile, mida Sul õnnestub leida.
5. Kirjelda domeriiti: värv, kihtide paksus, teralisus.
6. (pole kohustuslik) Lisa foto.

Palun saata vastused GC Message Center'is.

Kautliku cliff is the smallest of the north coast cliffs in Saare County. Maximal height in its central part is 2,5 metres. Even today, the cliff precipice is in an active coastal erosion zone and thus the face of the cliff changes constantly over time. The soft dolomitic marlstone, or domerite, from the Paramaja member o the Jaani stage is exposed along the entire cliff precipice. The local Jaani stage domerites are so clayey and bluish-grey in color that they seem more like clays. The rock is very pyrite-rich at times and little pyrite (fool's gold) nests can be found in the cliff wall upon closer looking. Kautliku cliff is one of the few domerite cliffs with no platy dolostones with bioherms in the upper part of the cross-section, which are so characteristic of the cliffs on the north coast; here the domerites are covered directly by the beach gravel and loose rubble. This is why the cliff is less resistant to natural forces too. The fossils found in the exposed rock of the Kautliku cliff wall give reason to believe that such rock types were formed in calm water sedimentation conditions and on the border of an open shelf. The deepest eater conditions in the Jaani age are associated with the existence of layers of volcanic ash. This indicates that the subsidence of the central axis of the Paleobaltic basin and an increased influx of clay material were connected to the increased volcanic activity.

Questions:

1. What is marlstone and what is domerite? Describe. (information board)
2. To which continent belonged Estonia during middle-Silurian? (information board)
3. Your opinion: how long is the cliff?
4. Describe fossiles what you can find at the cliff.
5. Describe domerite: color, layer thickness, grain size.
6. (optional) Add a photo.

Please send answers in GC Message Center.