Regional Variation in Parent Material and Its Influence on Critical Zone Processes of the Southeastern United States Coastal Plain.

A central focus of Critical Zone science is to understand and quantify how parent material impacts processes on Earth’s surface.  Accordingly, over the last 15 years great progress has been made towards reconciling how the pedosphere, hydrosphere, biosphere, atmosphere, and even anthrosphere vary depending on the properties of parent material directly underlying the Critical Zone (ie. residual landforms).  The majority of Earth’s Critical Zone however exists on depositional landforms, where parent material variation is controlled by transport processes rather than underlying lithology.  Here we conduct geospatial analyses of the Coastal Plain in the southeastern United States, from south Florida to North Carolina, to determine (1) the major drivers of parent material variation across this depositional landform, and (2) how parent material variation impacts Critical Zone processes.

We find that high and low energy depositional environments coincide with episodic marine regression (since the middle Pliocene) to control the distribution and properties of parent material across this large region.  We then demonstrate and discuss how this parent material variation is propagated into the contemporary Critical Zone to not only influence major processes in the pedosphere, hydrosphere, biosphere, atmosphere, and anthrosphere, but also their regional distribution.  Our work shows that Critical Zone processes on depositional landforms is highly dependent on parent material variation (similar to those on residual landforms), and highlights the importance of considering parent material variation on depositional landforms when investigating Earth surface processes at a regional scale.