The Paper outlines some qualitative field studies of fissure systems from various Cretaceous sediments in south-east England and presents definitions, classifications and conclusions resulting from the study. The work formed part of a programme investigating the possibility of determining fissure patterns in soft rocks to help in the analysis of the engineering behaviour of fissured sediments. To be in a position to predict fissure patterns it was thought necessary to investigate factors having a potential influence on Assuring. Sites chosen for field study were therefore selected to permit investigation of each factor separately. The main factors considered were the depositional environment, lithology bedding, stress release perpendicular to exposure and ground surfaces, tectonism, diagenesis, weathering and age of exposure. Results from each site were analysed by stereograms for the possible influence of each factor. All the sediments investigated were overconsolidated. In order to determine how the results of observations varied in different fissured materials, the Chalk, Gault and Weald Clays were examined in detail and results from allied work in the Barton, Bovey and London Clays were also considered. It was concluded that in general fissure patterns in the different materials were basically similar and differences between the patterns could be explained from a consideration of the geology. Classifications of fissures in terms of size, surface characters and geometry, fabric and intensity have been established. Techniques of measurement, recording and presentation were developed and from the results conclusions were drawn on the effect of fissure patterns and their potential relation to the engineering behaviour of the material in which they occur. © 1969, Thomas Telford Ltd. All rights reserved.
