Date: April 11, 2017
Time: 3:30 p.m.
Location: Slichter 3853
Coffee and cookies at 3:00 pm, Talk at 3:30 pm
Candidate: Mackenzie Day
Title: Sand in space: Allogenic versus autogenic controls on pattern development in aeolian systems
Abstract: Saltating sands generate regular patterns in nature depositionally by organizing into dune and ripple fields, and erosionally by carving yardangs and ventifacts. Dune fields in particular develop complex patterns through autogenic dune interactions within the field. Dune interactions are abundant in modern systems and their spatial density can be used as a proxy for dune field maturity. Crescentic and linear dune fields evolve along two distinct pathways, but typically only crescentic fields are preserved in the rock record. Although autogenic dune interactions drive the evolution of dune fields at the surface, allogenic controls on dune-field boundary conditions determine what, if any, of the dune strata are preserved. On Earth, aeolian systems are fundamentally limited by allogenic controls including tectonics and sea-level which can resurface landscapes faster than aeolian processes. On Mars, plate tectonics have been inactive and surface water absent for several billion years. Wind has become the dominant geomorphic agent on the Red Planet, and Mars constitutes an excellent natural laboratory for studying the unchecked progression of landscape evolution under purely autogenic forcings of aeolian sediment transport.
Intellectual Engagement: Speakers have been asked to prepare a 50-minute presentation and to reserve 10 minutes for questions and answers. During the first 50 minutes, brief requests for clarifications will be allowed. Substantive questions should be confined to the Q&A period. A moderator will manage the order of questions starting at the 50-minute mark. Questions related to the speaker's presentation will take priority over other comments.