Preferred orientation of orthoconic nautiloids in the Ludlovian Hemse Beds of Gotland

Abstract

An occurrence of preferred orientation of orthoconic nautiloids in the uppermost part of the Ludlovian Hemse Beds of southern Gotland, Sweden, is described. An analysis of their orientation shows a current direction roughly towards the present southeast in the western part of the island. Graphic and trigonometric computations of the strike and dip of the Hemse-Eke boundary surface were made and the results support the conclusion that the direction of currents was perpendicular to the shoreline. It is concluded that the direction of the shoreline varied from north-east in the western part of the island to east north-east in its central portion to northeast in the eastern part of Gotland during part of Ludlovian times. The silty components of the upper part of the Hemse Shale in east Gotland were probably transported from northeast.