Entisols are weakly-developed soils. The lack of strong development in these soils is often due to one of several factors: a persistent high water table (higher than in Inceptisols but not so high as in Histosols), a parent material composed mainly of quartz sand (as in the soil below, a sandy Entisol with only an A horizon over a C horizon), a location on an eroding slope (below...a scene showing Entisols on a slope in Wyoming) or on a very young landscape, or are extremely young because they have been recently disturbed by human activity. 
unstable_slope.JPEG (126655 bytes)

a_udipsamm_coloma.JPEG (49 kb)

Entisols are soils with little or no evidence of B horizon development and are found in three areas in the southern part of the Lower Peninsula. They are alluvial, or water-deposited, soils associated with the beds of glacial streams or with the sands and gravels of glacial outwash. They tend to be low in humus and dry out quickly because of the high sand or gravel content and are of limited importance in Michigan.
    Obviously, sandy Entisols (on uplands) can be droughty soils.  However, many of them have small amounts of clay, which infiltrating water reorganizes into thin clay bands called lamellae.  The sandy Entisol below shows such lamellae (red bands below 140 cm).  These clay bands can really "make the difference" between a highly droughty soil and one that is capable of supporting a dense and productive forest.
argic_udipsamment.GIF (241833 bytes)

Entisols are common in the western UP, where glaciers have scraped much of the landscape clean.  The thin, patchy glacial drift overlying hard bedrock restricts soil development, and the soils stay "entic".
thn_soil_bedrock.JPEG (142567 bytes)

The map below shows that, in the Great Lakes region, Entisols are commonplace.  The Psamments, or dry, sandy Entisols, are most common, given the large amounts of sand in the region.  Arents (purple on the map) are disturbed soils in urban areas like Chicago and Detroit.  Some areas of the Saginaw Lake Plain contain wet sands (Aquents).
entisols-suborders-map.jpeg (57632 bytes)
entisols-suborders-legend.jpeg (28660 bytes)

A more detailed map of the sandy Entisols can actually function as a map of sandy sediments in Michigan.  The sandiest moraines, outwash plains, and dunes show up nicely on such a map (below) as Psamments (also the image below). 
t_udipsamment_w_bs.JPEG (433214 bytes)

The orange areas are the young soils of river valleys, on shallow bedrock, and on the wettest sites of the lake plain.
soilmap-psamments.jpeg (64362 bytes)

Most soils that have been "created" by humans are considered Entisols.   Thus, the soils that is being "made" along this freeway bank would be man-made, yet classified as an Entisol.  Note how the construction crews have spread a thin layer of topsoil over the top of a scalped, sandy landform, with its C horizon of sand showing.
making_an_entisol.JPEG (81987 bytes)

Parts of the text on this page have been modified from L.M. Sommers' book entitled, "Michigan: A Geography".

This material has been compiled for educational use only, and may not be reproduced without permission.  One copy may be printed for personal use.  Please contact Randall Schaetzl (soils@msu.edu) for more information or permissions.