- PSB-South 2712
Daniel Livsey will present his PhD defense entitled "Holocene sea-level, climate, and estuarine stratrigraphy of Baffin Bay, Texas: studying past changes in coastal systems to elucidate future coastal response to changing sea-level and climate" on Thursday, August 20, 2015 at 2:00 PM in PSB-South 2712.
Recent studies along the northwestern Gulf of Mexico document rapid back-stepping of estuarine environments of up to 20 km and 150 m/yr at ca. 8.2 thousand years ago (ka), 4.8, ka, and 2.6 ka (Anderson and Rodriguez 2008). If such rapid changes in coastal environments occurred today along the urbanized coast of the Gulf of Mexico major economical and ecological loss would occur. Proposed forcing mechanisms for these back-stepping events include: increased sea-level rise, flooding of relict fluvial terraces, or a decrease in sediment supply. High-resolution, proximally derived, paleo sea-level, climate, and stratigraphic records are needed to understand: 1) how coastal systems responded to past changes in sea level and climate, 2) place current rates of sea-level rise and climate change into context, and 3) determine the risk of km-scale backstepping of coastal systems occurring over the next century. Paleo sea-level, climate, and stratigraphic records are presented to understand the Holocene stratigraphic evolution of upper Baffin Bay, Texas and determine the relative role changes in sea level and climate had upon estuarine environments. Baffin Bay is an excellent locality to study the coastal response to changes in sea level and climate given its location along the tectonically stable, low gradient, Texas coast and position along a steep North-South precipitation gradient. Five flooding surfaces, between 1.1 - 1.0 ka, 2.7 - 2.1 ka, 3.8 - 3.0 ka, 5.2 – 4.9 ka, and 6.5 – 5.7 ka (Livsey and Simms, in review) occur through a time-period of ever decreasing rates of relative sea-level rise (RSL) (Livsey and Simms, 2013) and within error of paleoclimate records that indicate drying in southern Texas (Livsey et al., in review). We hypothesize that these flooding surfaces, occurring when sea level in the Gulf of Mexico was rising < 2 mm/yr, and during independently documented drying events, were likely primarily driven by changes in climate through declines in fluvial sediment supply to the coast.