Soeginina pank on üks omapärasemaid ja kummastavamaid panku Saaremaal. Geoloogiliselt on pank iseäranis huvitav oma paljanduvate kivimite kirju koostise poolest. Järsaku peal kasvav mets on eriti hilissügisel oma väänduvate raagus puude ja võsaga ning üle panga ääre rippuvate ja pragudesse tunginud juurterägastikuga lausa kummitusliku väljanägemisega.
Panga pikkus on umbes 500m, mõningate hinnangute järgi üle 1km. Nii maksimaalset kõrgust kui ka aluspinnalist läbilõiget on umbes 3,6m. Panga seinas avanevad Vesiku kihtide kivimid ja Soeginina kihtide tüüpläbilõige. Rootsiküla ladet iseloomustab Siluri ajastul meie alal asunud Paleobalti mere väga madalaveelised tingimused. Kogu Soeginina pangal avanev kihtide kompleks on tõenäoliselt tekkinud magestunud madalas laguunis. Sellele viitavad nii spetsiifilised kivististe kooslused, kõrge terrigeense materjali sisaldus kivimis kui ka mitmetel kihtpindadel esinevad kuivalõhed.
Panga allosas, rohkem kui 1,5m paksuses eriilmelises kihis paljanduvad Vesiku kihtide dolokivid. Paaril tasemel on selged katkestuspinnad: kivimis jälgitavad sakilised või sissesopistustega markerpiirid. Kohatised tugevad katkestuspinnad võivad viidata mitmele tegurile, kuid tavapärane järjepidev settimine on sel ajal katkenud.
Rootsiküla lademe dolokivid lõpevad 15cm paksuse pruunikashalli savika ja üksikute onkoliitidega dolokiviga. Rootsiküla dolokivide peal lasuvad Soeginina kihtide erineva paksusega dolokivid. Iseloomuliku struktuuri pärast kutsutakse seda kivimit sibulapaeks.
Küsimused (palun vastuseid messengeris):
1. Millistesse kahte Siluri ajastusse jääb Soeginina pankade eri kihtide tekkimisaeg (infotahvel)?
2. Kirjelda panga läbilõiget skeemi järgi ja oma sõnadega tuginedes otsesele vaatlusele.
3. Nimeta, milliseid fossiile siit pangalt on leitud (infotahvel)
4. Proovi leida fossiile. Kui soovid pilte lisada, siis see on teretulnud.
Soeginina cliff is probably one of the most unique and weird cliffs in Saaremaa. Geologically, the cliff is especially interesting because of the colourful consistency of the exposed rocks. The forest growing on the precipice looks haunting, especially in late fall because of the winding bare trees and underbrush as well as the root maze hanging over the cliff's edge and boring into its crevices.
The length of the cliff is about 500m, or even over 1km according to some estimates. Its maximal height and geological cross-section is about 3.6m. The cliff wall is the stratotype of the Rootsikula stage. The Rootsikula stage is described by the extremely shallow water conditions of the Paleo-baltic Sea that was situated here in the Silurian era. The entire layer complex visible on Soeginina cliff probably formed in a desalinated shallow lagoon. The specific fossilised biotic communities (mainly 1-2 species), a high concentra-tion of terrigenous material (sand-clay) in the rock (possibly carried along by rivers), as well as the mudcracks that appear in several layers all point to this.
Dolostones of the Rootsikula stage are exposed at the bottom of the cliff, in a 1.5m-thick diverse-looking section. Some levels display obvious discontinuity surfaces: jagged or indented layers are visible in the rock. Distinct discontinuity surfaces can indicate several possible changes, but it is certain that ordinary consistent sedimentation has come to a halt during that period. By studying in detail the consistency of the rocks and the fossils present in the bedrock, it is possible to find the exposed layers that have settled at the same time and conditions over tens, hundreds and even thousands of kilometres, even if the layers are hidden under a thick layer of sediment in between.
The Rootsikula dolostones are covered by the different dolostone of the Paadla stage. Because of its characteristic spherical and layered structure the rock is called "onion limestone".
Questions to answer (in Messenger, please):
1. In which two Silurian epoches does the time of formation of different layers of Soeginina cliff (information board) fall?
2. Describe the cross-section of the cliff according to the scheme and in your own words based on direct observation.
3. Name which fossils have been found at this cliff (information board)
4. Try to find fossils. If you want to add pictures, this is welcome.
