The Sundvollen Formation is a geologic formation cropping out along the northern and eastern shores of Steinsfjorden, Oslo Region, Norway. It preserves fossils dating back to the Gorstian to Ludfordian stages (Rootsiküla in the regional stratigraphy) of the Late Silurian period.Sundvollen Formation at Fossilworks.org
Description The formation belongs to the Ringerike Group,Bremer et al., 2019, p.129 overlies the Steinsfjorden Formation and is overlain by the Stubdal Formation. The fish assemblage originates from a horizon with fine-grained, dark greyish-green sandstone from the lowermost part of the formation.
The formation comprises dark-grey siltstones associated with red sandstones and siltstones, with ripple marks, cross-laminations, and crack diapirs, and pseudo-nodules, carbonate concretions. The sequence is fining upwards in cyclothems. Tracks attributed to eurypterids have been found in the red siltstone. Turner (1974) interprets the Sundvollen Formation as representing meandering, braided streams on an alluvial, coastal plain, very close to sea level because of the minor marine incursions found). Boucot and Janis (1983) interpreted the environment to be possibly brackish-estuarine.Eurypterid-Associated Biota of the Sundvollen Form. at Rudstangen at Fossilworks.org
Fossil content The following fossils have been reported from the formation:
Fish
Ateleaspis sp. Loganellia cf. aldridgeiBremer et al., 2019, p.142 Paralogania martinssoniBremer et al., 2019, p.144 Phlebolepis elegansBaarli et al., 1999 Pterygolepis cf. nitida Rhyncholepis parvulaBremer et al., 2019, p.145 Thelodus laevis Tyriaspis cf. whiteiBremer et al., 2019, p.146 Osteostraci indet.
Eurypterids
Brachyopterella pentagonalis Eurypterus tetragonophthalmusPlotnick, 1999 Kiaeropterus ruedemanni Mixopterus kiaeri Nanahughmilleria norvegica Pterygotus (Erettopterus) Erettopterus holmi Stylonuroides dolichopteroides Mixopterus sp. Nanahughmilleria sp. Pterygotus sp.
Invertebrates Crustaceans Phyllocarida indet.
Chasmataspidids Kiaeria limuloides
Xiphosura Xiphosurida indet. Bunodes sp.
Flora Plantae indet. Dictyocaris slimoni.
Correlations The Sundvollen Formation correlates with the lower part of the Store Arøya Formation.Bremer et al., 2019, p.132
See also List of fossiliferous stratigraphic units in Norway
References
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