The limited geographical extent of Jotnian sediments at present is indebted to their erosion over geological time. Sedimentary rocks as old as the Jotnian sediments age have a low preservation potential. The distribution of some Jotnian sediments is spatially associated with the occurrence of rapakivi granite. Korja and co-workers (1993) claim the Jotnian sediment–rapakivi granite coincidence at the Gulf of Finland and the Gulf of Bothnia is associated with the existence of thin crust at these locations. At present Jotnian sedimentary rocks are commonly found in half-grabens, narrow grabens, in slightly downfolded (syncline) positions or in mixed graben-synclines. Most of the grabens hosting Jotnian sediments are northwest-southeast oriented. The largest occurrence of Jotnian sediments appear however to occur neither in a rift or a graben and lie in Dalarna, Sweden. It has been suggested that the sedimentary basins hosting Jotnian sediments at Dalarna, Gävle, the Bothnian Sea, Satakunta and Lake Ladoga form an alignment of subsidence parallel to the area of inferred Hallandian-Danopolonian subduction, possibly corresponding to an ancient back-arc basin. Between Finland and Sweden Jotnian sediments are common in the Gulf of Bothnia, the Bothnian Sea and the Åland Sea including South Kvarken. Known Jotnian rocks at the Åland Sea are sandstones and belong to the Söderarm Formation (informal). Above these there are Upper riphean and Vendian sandstones and shales. Fully within Swedish waters there is a Jotnian sediment occurrence at the Landsort Basin between Gotland and Stockholm archipelago. Jotnian rocks found in the Landsort Basin are red sandstones. In the Bothnian Sea offshore Pori in Satakunta Jotnian sediments reaches a thickness of thousand metres, in other locations thickness is much less, for example 100 m at the Sylen shoal and yet in other places of the Bothnian Sea Jotnian sediments are absent. The Sub-Cambrian peneplain cuts across Jotnian rocks in the Bothnian Sea. Muhos in the northeastern Gulf of Bothnia is a site of Jotnian sediment occurrence. At this location Jotnian sediments can be found within the Muhos Graben that has had a downward displacement of about one kilometre.