Just Dirt?

Here at the Governor Institute, we began to observe the various layers and types of soil surrounding the Indian Brook Reservoir. Each sample of soil told us something different about the area. How water carries minerals and nutrients through the soil, and how the amount of nutrients and minerals decreases as the soil deepens. This concludes the general observation that the upper layers of the soil are the most fertile in minerals and nutrients.

The soil surrounding the Indian Brook Reservoir differs in many ways. It varies in the amount of organic material decomposing, the color of the soil, and the depth of the various layers of soil (horizons).

There are many different horizons in the soil community, however the most dominant ones found on Indian Brook Reservoir are the O, A, E and B-horizons. The "O" horizon is often referred to as the "organic" horizon. It consists primarily of decomposing materials, such as pine needles, leaves, trees, animals, and roots.

The "A" horizon has little significance in the forest. Rather, it has more agricultural use. This soil is very rich in minerals, and has a great amount of organic influence.

The "E" horizon often follows the "O" horizon. It was gray in color, and blended in with a top layer of "O" horizon and a bottom "B" horizon layer.

This "B" horizon contains oxidized iron, which results in a red-orange tint of the soil.

We began our research at site number one (displayed on the map). We took a core soil sample with an auger (device used to collect a sample of soil), in order to distinguish the horizons in the soil.

Site 1) Our first sample had an obvious "O" horizon. This horizon consisted of organic, dark brown, decomposing pine needles, leaves, etc. Below the "O" horizon was a clear "E" horizon, which was gray and was composed of fewer nutrients than the "O" horizon. Following the "E" horizon was a "B" horizon that was reddish and contained even fewer nutrients than the "E" horizon. This soil was very fine and will crumble in your hands.

Site 3) The third site was taken near what appeared to be the backyard of an old house, with nothing left but the stone basement. This sample was just as we would have guessed it would be like, all organic. This highly organic soil would suggest that this area has always been filled with grass and has continued to decompose. The presence of a stone wall around the area posed the question of maybe an animal grazing area, which would also contribute to the decomposing organic soil.

Site 4) The fourth site was located roughly 10-15ft away from Indian Brook. wide. At this site, the organic layer was scarce, and we found a large layer of clay with no defined horizons. From this we can conclude that at one point the brook had a larger basin that covered this area. This basin may have wiped away all of the nutrient rich layers of the soil, leaving bare clay.

Site7) The seventh site had a large organic horizon that blended drained into the "B" horizon. This "B" horizon embodied a reddish tint caused by oxidized iron. Oxidized means the soil has given up electrons to change its tint.

Sites 8+ 9) Stops eight and nine contained large gray horizons, such as the ones found by the riverbed. Both of these sites were located within 40 ft of the actual reservoir, which suggests that these points were also covered by water at one point. This water evidently eroded all of the organic matter.

Example of the reddish soil dug up by an uprooted tree

Site 10) Our final site was very similar to our first site. There were three distinct horizons (O, E, and B), all equal in depth.

From all of these sites you can tell a lot about the area today and hundreds of years ago. After observing the area and soils, we can conclude that the land surrounding the reservoir was used for farming and grazing, at one point. We can tell the reservoir and tributaries were once much bigger, by the soils found above them, and their absence of organic layers. We can tell it was a farming area by the stone walls all around, which were probably used for animal entrapment. Also, the very organic layer covering the majority of the forest suggests the grazing in what was formerly grass.