Sedimentary structures and palaeocurrent directions from the Silurian rocks of Kirkcudbright

Abstract

New sedimentary structures are described from a thick greywacke/mudstone succession. The structures include modified ripple marks, nodule trails and orthocone prod marks. Further evidence is given and comment made on the genesis of longitudinal ridges, chevron marks and large-scale current bedding. Palaeocurrent directions statistically determined from 353 observations show that the dominant turbidity currents during Riccarton (Wenlock) and Upper (?) Silurian times came from the north-east ( i.e. parallel to the axis of the Caledonian geosyncline) with minor currents from the south-west. Currents at right angles to the axis of the geosyncline deposited the transverse ripples.