Soils in the Adirondack Mountains are relatively young, having formed in sediments deposited from the last major glacial episode that ended in the Adirondacks about 12,000 years ago. Most of the region is covered by an acidic, sandy, low-fertility soil called a Spodosol. Over time, Spodosols develop distinct colorful horizons that can be clearly distinguished in soil pits and road cuts. Because Spodosols are naturally acidic and contain marginal concentrations of some elements necessary to sustain a healthy forested ecosystem, they are somewhat fragile and susceptible to chemical changes. A century’s worth of acid deposition (“acid rain”) has depleted these soils of some important nutrients and has mobilized aluminum, an element linked to fish mortality and forest decline. Acid rain has declined over the past several decades, and lakes, streams, and soils are beginning to recover. How long it will take is still unknown.



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