The Holland Paleosol: an informal pedostratigraphic unit in the coastal dunes of southeastern Lake Michigan

Abstract

A very prominent buried soil crops out in coastal sand dunes along an ~200 km section of the southeastern shore of Lake Michigan. This study is the first to investigate the character of this soil — informally described here as the Holland Paleosol — by focusing on six sites from Indiana Dunes National Lakeshore north to Montague, Michigan. Most dunes in this region are large (>40 m high) and contain numerous buried soils that indicate periods of reduced sand supply and comcomitant stabilization. Most of these soils are buried in the lower part of the dunes and are thin Entisols. The soil described here, in contrast, is relatively well developed, is buried in the upper part of many dunes, and formed by podzolization under forest vegetation. Radiocarbon dates indicate that this soil formed between ~3000 and 300 calibrated years BP. Pedons of the Holland Paleosol range in development from thick Entisols (Regosols) with A–Bw–BC–C horizonation to weakly developed Spodosols (Podzols) with A–E–Bs–Bw–BC–C profiles. Many profiles have overthickened and (or) stratified A horizons, indicative of slow and episodic burial. Differences in development are mainly due to paleolandscape position and variations in paleoclimate among the sites. The Holland Paleosol is significant because it represents a relatively long period of landscape stability in coastal dunes over a broad (200 km) area. This period of stability was concurrent with numerous fluctuations in Lake Michigan. Given the general sensitivity of coastal dunes to prehistoric lake-level fluctuations, the soil may reflect a time when the lake shore was farther west than it is today. The Holland Paleosol would probably qualify as a formal pedostratigraphic unit if it were buried by a formal lithostratgraphic or allostratigraphic unit.