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The first geological record of a palaeotsunami on the southern coast of the Baltic Sea, Poland

Rotnicki K., Rotnicka J., Goslar T., Wawrzynniak-Wydrowska B.

Geological Quarterly

2016

Vol. 60, No. 2

417--440

Tsunami deposits were unknown along the southern coast of the Baltic Sea for a long time. The results of present research provided evidence of high-energy event layers. They occur on the bottom of two hemispherical hollows that are cut into glaciolimnic silt and glaciofluvial sand and gravel from the Late Weichselian Age. The event deposits are represented by poorly sorted marine sand with admixtures of pebbles and allochthonous detritus of biogenic origin: marine, brackish and occasionally freshwater shells and shell debris of molluscs and snails, plant macrofossils from the marine nearshore zone, shreds and lumps of peaty material, gyttja and organogenic silt, lumps of charcoal, wood pieces and tree branches and trunks. All these features are commonly considered indicative of tsunamis. The age of the biogenic detritus found in the tsunami layer ranges from 10 390 to 6 630 cal. yr BP, whereas the oldest gyttja covering the event layers is 6 600 cal. yr BP old. This means that the tsunami occurred between 6 630 and 6 600 cal. yr BP. Various causes of tsunami event have been taken into consideration, including the impact of meteorites within the coastal plain and the littoral zone of the southern Baltic Sea.

Ichnofabrics of the Upper Cretaceous fine-grained rocks from the Stołowe Mountains (Sudetes, SW Poland)

Rotnicka J.

Geological Quarterly

2005

Vol. 49, No. 1

15--30

Upper Cretaceous fine-grained rocks (the “Plänermergel”) from the Stołowe Mountains are in general strongly bioturbated. The sections studied (180 m thick), located in the southern part of the mountains, are dominated by mudstones, marlstones and siltstones; sandstones, partly unbioturbated, are subordinate. The entire sequence shows a succession of ichnofabrics, which reflects a transgressive-regressive cycle (Cenomanian) and a regressive cycle (lower to middle/upper? Turonian). The trace fossil assemblage contains nine ichnogenera: Asterosoma, Cylindrichnus, Ophiomorpha, Palaeophycus, Phycosiphon, Planolites, Taenidium, Teichichnus, and Thalassinoides. Three basic types of ichnofabrics have been recognized: Ophiomorpha, Thalassinoides and Phycosiphon, all representing fully marine ichnofacies. The first two of these belong to the Cruziana ichnofacies, indicating the offshore zone, and the third one probably to the Zoophycos ichnofacies indicating a quiet shelfal setting below storm wave base.