Current Research in EEPS: Dr. Vamsi Ganti, UC Santa Barbara
Morphodynamic Hierarchy and the Fabric of the Sedimentary Record
Earth’s ability to archive its evolution in sedimentary rocks forms the basis of our knowledge of past environments and life. The amount of preserved time, however, is vanishingly small, which could indicate that preserved strata preferentially record the catastrophic and extreme events of the geologic past. Contrary to this expectation, field evidence across a multitude of scales suggests that fluvial strata predominantly record the mundane and relatively common transport conditions—a paradox termed the strange ordinariness of fluvial strata. Using a new probabilistic modeling framework, and existing experimental and field data, I will show that the strange ordinariness of fluvial strata is a result of the propensity of rivers to organize themselves into hierarchical elements (e.g., river dunes, bars, channels, channel belts) that each have their representative timescale of evolution. Results demonstrate that the presence of this hierarchy reconciles the paradox between the rarity of event preservation and the familiarity of the preserved events in stratigraphy at all scales. I will also show that when successive hierarchical elements evolve at comparable rates, ordinary events are more likely to be preserved in stratigraphy. Finally, I will highlight how relative changes in kinematic rates of evolution in successive hierarchies can manifest as major shifts in stratigraphic architecture through Earth history. The story written in rocks is mostly of common events and conditions, not the rare and spectacular.
