Subaqueous Soils Mapping

Introduction to Subaqueous Soils.

NRCS and MapCoast have been mapping subaqueous soils in Rhode Island’s coastal lagoons and in Narragansett Bay following similar protocols and methods used by traditional soil scientists on land. A critical first step in this mapping is the identification of shallow-subtidal landscapes (JPG, 1.4 MB). These are delineated in lab using recent and high resolution bathymetry, aerial photography, and an understanding of geologic coastal processes. For full descriptions and definitions of subaqueous landscape units, click here.

An oblique view of Quonochontaug Pond showing seamless bathymetry and subtidal landscape units.

The landscape units identify areas to sample and describe subaqueous soils in the field. For examples of our field descriptions and vibra-core data click here and here. Please refer to this list for commonly used abbreviations in these descripitions and the soils textural triangle for texture classes.

Field descriptions, vibra-core information, and lab data are then used to classify each soil using the subaqueous soil taxonomy (please refer toNinigret Pilot Study report for a copy of the taxonomy,disclaimer: draft only). Subaqueous soil classifications, landscape position, and physical and chemical characteristics are then interpreteded to identify and delineate the subaqueous soil map units(PDF, 22 kb). This document describes the map units found on the MapCoast IMS site. Presently, NRCS in New England has identified ~9 subaqueous soil series which are presently under review.

Dr. Mark Stolt and Al Averill of the NRCS NE Regional office look over a highly stratified vibra-core.

 

USDA – NRCS soil texture classes with Shepards (1954) grain size classes (in red)
Source: Bryan Oakley. (click image to open full-size in new window)