GSA Annual Meeting in Phoenix, Arizona, USA - 2019

Paper No. 173-1
Presentation Time: 8:00 AM


WANLESS, Harold R., Geography and Regional Studies, Univ of Miami, P.O. Box 249176, Coral Gables, FL 33124

My Senior Thesis Advisor, Alfred Fischer, reinforced my family history that the Earth's story is in the sedimentary rock sequences and that there may be much more than one story there. This served through my Masters (refining the late Holocene clastic, carbonate, and organic sequences in Biscayne Bay, Florida) and Ph.D. (documenting the meter-scale fundamental cycles of sedimentation in the Grand Canyon Cambrian within the previously documented larger shale to limestone cycle groupings).

More recently my students and I – and many others – have striven to refine the details of the post glacial maximum sea-level rise over the past 18,000 years. We have learned that during a time of warming, with ice present, sea level rises in a series of pulses and pauses as one ice sheet sector after another rapidly disintegrates. During slow-/still-stand periods between pulses, significant coastal sediment bodies (reefs, sandy barrier islands, tidal inlet deltas, bay head deltas, and coastal mud flats and wetlands) may form and be preserved as they are over stepped during the next pulse of rise. As a result, sediment bodies are preserved across our continental shelves as testament.

As overall ice melt and sea level slowed during the past 5,000 years, there were still smaller pulses of rapid rise which have produced distinct sediment bodies, but these are commonly superimposed onto/into one another rather than being laterally offset. These composite high-stand sequences create a much different and more complex pattern of sediment facies than the simple single high-stand sea level deposit commonlly considered. Similar multiple sea level facies complexes are also now being recognized in the Eemian high stand of the previous interglacial.

This refined understanding of the nature of our post-glacial sea level rise also provides the only solid foundation from which to consider future response to anthropogenic warming and ice melt.