Micromorphology of seasonally saturated soils in carboniferous glacial till

Soils formed in dark-colored glacial till (chroma 3, value < 4) are common in southern New England, The low chroma, low-value colors reflect the carbo niferous nature of the sedimentary and metasedimentary rocks that compose t he till. Much of this till is very dense, resulting in soils with seasonal high water tables. The inherent dark colors of the soils make it difficult to use hydromorphic features to estimate depths of seasonal saturation. We examined thin sections to determine if micromorphology could be used to elu cidate the apparent lack of hydromorphic features in seasonally saturated B w horizons formed in dark till. Observation wells were monitored for 18 mon ths to establish water table seasonal fluctuations in soils on shoulder pos itions. Hydromorphic features were examined in the field and in thin sectio ns to correlate with the seasonal water table levels. Soils showed seasonal saturation and were classified as Humic Epiaquepts and Typic Humaquepts. W ater levels frequently rose into the upper Bw horizons. One of the soils ex amined met hydric soil criteria based on hydrology, Hydric soil indicators such as a depleted matrix (F3) were absent. The dark parent materials were most likely preventing the observation of morphologic indicators of reducin g conditions. Redoximorphic features were not identified by field observati ons in the seasonally saturated upper Bw horizons. Thin sections of the upp er Bw horizons revealed redoximorphic features that were too faint, fine, o r had boundaries too diffuse to be observed in the field. Identifying hydro morphic features in lower horizons and, with the aid of magnification, trac ing these features carefully into overlying horizons may help identify the depth to aquic conditions in low chroma-low value seasonally saturated soil s.