Continental rift basins have long been of interest to sedimen-tologists. Of all the terrestrial depositional settings, rift basins typically provide the greatest accommodation space, and consequently have some of the longest records of continental sedimentation. These records are a product of a complex interplay between several factors. These include geological structure and tectonic activity, volcanism, climate and its temporal variability, hydrology, hydrogeology, biology, and time (Fig. 1). The lithological records in rifts, which are naturally dominated by fluvial and lacustrine deposits, have become increasingly prominent in recent years because of their potential for studying long-term climatic changes and for testing hypotheses of orbital forcing (e.g., Olsen, 1986; Johnson and Odada, 1996). More recently, the continuing quest for the paleontological and cultural records of human origins that are entombed in the sedimentary rocks of the East African rift has raised further questions on the tempo of climatic change, changing paleolandscapes, and the environmental stresses that might have affected human evolution (Vrba et al., 1995; Andrews and Banham, 1999). Rapid burial of thick sedimentary fills, high geothermal gradients, and consequent early maturation of lacustrine organic matter, much of which is sapropelic, have made rift basins attractive targets for petroleum exploration (e.g., Robbins, 1983; Katz, 1990; Lambiase, 1990, 1995). Indeed, most of our understanding of rift-basin geometry has resulted from seismic profiling sponsored by oil companies (Scholz et al., 1990; 1996;
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Sedimentation in Continental Rifts
Continental rift basins have long been of interest to sedimentologists. Of all the terrestrial settings, rift basins typically provide the greatest accommodation space, and consequently have some of the longest records of continental sedimentation. These records are a product of a complex interplay between several factors that include geological structure and tectonic activity, volcanism, climate and its temporal variability, hydrology, biology and time. Sedimentation in Continental Rifts is a timely update on this exciting interdisciplinary field and presents new approaches and insights into tectonic and structural controls of sedimentation. Other topics included are lacustrine and fluviatile depositional environments and some lesser-known settings, such as springs, wetlands, and paleosols. Several papers consider the behavior of silica in rift lakes, particularly the roles of microorganisms in silica precipitation, whereas others examine the paleoenvironmental importance of freshwater carbonates. The contents of the volume show that sedimentological research in rift basins has progressed beyond basic facies description and general models, and is now focused on understanding the integrative effects of physical, chemical and biological processes in rifts.