The forests on the slopes surrounding the stream were never cleared and the soils never farmed. The photo shows a soil probe taken about 100 feet from the stream bed in the lower reaches of Stebbins Gulch. Starting at the top of the core, we first see an inch or two of rotting leaf litter, an important source of recycled nutrients for the forest. The leaf litter is underlain by about four inches of an organically rich layer of dark humus. Humus greatly increases a soil’s ability to hold water, equally important for maintaining a healthy forest. Depending on many variables, it can take about 100 years for an inch of soil to form in a forest. This core represents a 400-to-600-year accumulation. Imagine how easily the top layer could be lost to erosion. Underlying the organic layers in the core is an inch or two of yellowish silty clay that probably goes down several feet before hitting bedrock.
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