Conglomerate, Emphasizing Fluvial and Alluvial Fan Environments
In the first edition of these notes (Harms et al., 1975), it seemed timely to review conglomeratic depositional systems, and the ways in which the sedimentary structures in conglomerate could be used to reconstruct transport processes and depositional environments. Since 1975, conglomerates of various environments have received more attention. We will limit our present discussion to fluvial systems, to that this chapter logically follows the previous one, yet still illustrates how environments can be reconstructed from primary structures and stratification sequences.
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Structures and Sequences in Clastic Rocks
These notes are for a course on the use of primary structures and stratification sequence as tools for interpretation of depositional environments. The emphasis is to provide a concise review of the factors that had led to the renaissance in clastic sedimentology during the decade leading up to 1975. The attempt is to provide an organized summary of both experimental studies and ideas on bed forms and primary sedimentary structures that was then relatively new and to show how this information could be applied to solving geologic problems. A second broad objective of the course is more philosophical, in that there is an attempt to outline some general approaches to interpretation and convey the goals of interpretation. The authors believe that there are a fairly small number of general depositional settings but that numerous environmental and process variables within each general setting lend considerable variation to the deposits themselves. The emphasis is at the scale of features and sequence that can commonly be observed in individual outcrops or cores. Interpretation begins with data collected at this level.