Chesuncook Soil Series

The Chesuncook soil series is Maine's official state soil. It sits on the nearly flat and gently sloping glaciated uplands of northern and western Maine — land that has been saturated with water for most of each year since the last glacier retreated roughly 13,000 years ago.

Chesuncook is one of the few state soils in the country chosen not for agricultural productivity but for ecological significance. Very poorly drained, cold, and acidic, it cannot be farmed without massive drainage and amendment. Instead, it supports the boreal forest that defines Maine's wilderness interior — black spruce, balsam fir, tamarack, and white cedar growing on a spongy mat of sphagnum moss and decomposing organic matter.

The soil stays wet because it forms in dense glacial till that water cannot drain through easily. Snow from Maine's long winters melts slowly on flat ground with nowhere to go. The result is a soil that is effectively waterlogged from snowmelt through late summer most years, frozen solid from late autumn through early spring.

The Chesuncook series is named for Chesuncook Lake, a large wilderness lake on the West Branch of the Penobscot River in Piscataquis County. USDA soil scientists established the series in this area, where very poorly drained glacial soils under boreal forest cover millions of acres of Maine's northern interior.

Henry David Thoreau traveled through the Chesuncook region in 1853 on a canoe trip through the Maine woods, and wrote about it in his book The Maine Woods, published in 1864. The Chesuncook wilderness he described — remote lakes, vast spruce forest, moose in the shallows — is the same landscape that the Chesuncook soil series underlies today.

The Maine Legislature designated the Chesuncook series as the official state soil in 1999. Soil scientists and conservationists supported the designation not because the soil is productive farmland — it is not — but because it best represents Maine's most distinctive landscape: the great north woods, glacially shaped, perpetually wet, and ecologically irreplaceable.

The Chesuncook profile is built from the top down by slow accumulation and from the bottom up by glacial deposition. At the surface is a thick organic layer — leaves, needles, moss, and partially decomposed matter that builds up because cold temperatures and waterlogging slow decomposition almost to a stop. Below it, the mineral soil is gray throughout, the signature color of a soil that stays saturated and oxygen-depleted.

That gray color is called gleying. In a waterlogged soil, oxygen is consumed by bacteria and never replenished. Without oxygen, iron in the soil is chemically reduced — it changes from its normal rust-brown form to a soluble form that washes away, leaving the soil pale gray or greenish gray. Gleyed soil is one of the clearest signs in the landscape that water sits here year-round.

Chesuncook soil is found across the northern and western interior of Maine — the vast, roadless landscape of Piscataquis, Somerset, Aroostook, and Penobscot counties that comprises some of the largest undeveloped land east of the Mississippi River.

The soil sits on nearly flat or gently sloping glaciated uplands where drainage is poor and water has nowhere to go after snowmelt. It fills the low spots between rocky ridges, the edges of bogs and fens, and the broad flat areas between river valleys — the landscape that looks uniformly forested from the air but is underlain by saturated soil just inches below the moss.

Chesuncook Lake itself, in Piscataquis County, is surrounded by this soil. The lake was dammed in the twentieth century to control water levels for the timber industry, and the boreal wetland soils around it are largely intact — one of the reasons the area remains important wildlife habitat for moose, loon, and Canada lynx.

Chesuncook soil is not farmland and never has been. Very poorly drained, cold, and acidic, it requires no agricultural management section — it manages itself. The forest it supports is instead Maine's most significant economic resource: timber.

Black spruce and balsam fir are the primary trees on Chesuncook soil. Both species tolerate waterlogged, acidic conditions that would kill most other commercially valuable trees. Spruce-fir forest on poorly drained soils like Chesuncook covers millions of acres of the Maine north woods and supplies pulp mills, paper mills, and lumber operations that have defined the Maine economy since the nineteenth century.

Tamarack — the only deciduous conifer native to Maine — also grows on Chesuncook soil, particularly in the wettest depressions. Tamarack needles turn gold and drop each autumn, leaving ghostly gray trees standing in the frozen bogs through winter. White cedar grows on the slightly better-drained edges of the Chesuncook soil landscape.

Moose are the most visible wildlife on this soil. Chesuncook and similar boreal wetland soils support the highest moose densities in the eastern United States. The wet, saturated conditions create the aquatic vegetation and thermal cover moose prefer in summer.