Perhaps one of the least understood, yet vitally important, layers of the landscape is soil – a mixture of sediment, organic material, water, and air which is constantly forming from the weathering of bedrock and surficial materials, and the accumulation of dead organic matter.
Localized differences in the underlying parent material, topography, and hydrology result in distinct soil varieties forming from one place to the next. Specifically, the glacial till that covers the hills on the eastern side of Hinesburg has weathered to form soils with a texture called loam that contain various combinations of sand, silt, and clay sized particles. Mixed in also are an abundance of gravel and cobble sized stones, the ground up remnants of glacial scouring. On the ridgelines of places like Texas and Lincoln Hill the soil layers tend to be thin and bedrock pokes through, while the flanks and base of the slopes often accumulate a thicker covering.
In contrast, the flat valley areas west of Route 116 have deep soils that are mainly derived from the fertile silts and muds that were deposited in the still waters of post-glacial Lake Vermont and the Champlain Sea, between 9,000-12,000 years ago. There are also a few places, like parts of the Bissonette Farm, where enriched “sweet” soils form from the underlying carbonate rocks. In addition to lacking the cumbersome stones that occur on the hillsides, these valley sediments are abundant sources of nutrients like calcium and magnesium for both native and cultivated vegetation. Indeed, since Hinesburg was founded more than 200 years ago, the soils of the Champlain Valley have served as an important component of the town’s bread basket. The fine texture of these soils can also be a nuisance, however; their excessive ability to hold water means that they take longer to warm up and dry out in the spring, which can hinder plowing and planting of crops.
The youngest soils on the Hinesburg landscape are located along the floodplains of active waterways like the LaPlatte River and Lewis Creek. Thanks to porous sand, these soils tend to be well-drained. They are also nutrient-rich, due to the steady input of fine-textured silt and clay in seasonal floodwaters. Still in other areas, like low-lying marshes and swamps and around beaver-ponds, the soil remains saturated from season to season, preventing the decomposition of organic material, and resulting in the accumulation of peat.
Despite these regional generalizations, soils are highly variable, even on the scale of single property parcels. For example, the 837 acres of the Hinesburg Town Forest are home to five different soil types, with varying degrees of nutrient enrichment. Each soil type, furthermore, is associated with a unique natural community of plants. In this way, soils play a fundamental role in influencing the local distribution of flora and fauna.
The importance of soil and its connections to our daily lives cannot be overstated either. So many of the basic resources we use, like food, water, fabrics, wood, and leather come directly or indirectly from the earth. The soil also stores vast quantities of atmospheric carbon – one of the main culprits in current global warming trends. Moreover, productive soil is a valuable, limited commodity. Hinesburg’s soils are the culmination of natural processes that took thousands of years to carry out since the glaciers retreated. One inch of productive soil may take up to 100 years to form! Yet it can be destroyed in a fraction of the time by the erosive powers of wind and water, and by the accumulation of excess synthetic fertilizers, pesticides, and salts. Without a doubt, soil is an indispensable component in the health and well-being of plants, animals, and human populations.