The Ordovician succession is characterized by flat-bedded 'orthoceratite limestone', belonging to the 'Latorp', 'Lanna' and 'Holen' limestones (topoformations; Figs 2B, H, 3, 4).
The water depth at which the 'orthoceratite limestone' was formed, and indeed much of the Baltoscandian palaeobasin, has long been a point of scientific debate and it remains a contentious issue.
These would be placed within a group corresponding to some version of the 'orthoceratite limestone', or alternatively as members should the latter be regarded as a single large formation.
The microfacies characteristics of the Ordovician 'orthoceratite limestone' at Lanna vary considerably throughout the studied succession, likely in large part due to changes in (relative) sea level.
Cephalopod Septal Strength Indices (SSI) and the depositional depth of Swedish Orthoceratite limestone.
Stenoblepharum includes the earliest tropidocoryphids (and Proetoidea) from Baltoscandia, being present in geschiebe of Red Orthoceratite Limestone, of late Darriwilian age, from northern Germany (Popp & Schoning 2006).
But its occurrence in mid-Darriwilian geschiebe of Red Orthoceratite Limestone (Popp & Schoning 2006) indicates its presence at that time within the Central Baltoscandian CB.