Soils and Geology

Results of Soil Pit:

Soil from pit
Photo Credit: Kristen Wade

In order to determine soil type on our plot we dug a soil pit in an area that accurately represented the way our plot was constructed. This pit was about one and a half feet in depth.  The purpose of this is to be able to observe the changes in soil composition as the depth increased.  By carefully piling the soil onto a tarp we were able to see color changes that represented a variation in soil composition.  Our soil’s coloration was very similar which indicated its homogenous nature.  Upon further examination we determined that the soil layers were as follows:

BC: Clay

BW: Silty Clay

B: Silty Clay Loam

A: Duff (organic matter)

*Each layer was also found to have a pH of 7 (neutral).  

By determining the location of our plot and studying a map of Niquette Bay State Park we determined that the surficial geology beneath our plot is Champlain sea clay and the bedrock was found to be Monkton formation.  

This is a map of a cross-section in our plot. The bed rock was Monkton formation, Surficial Geology is Champlain Sea Clay, and the soil type was HnE. 

The results of the soil pit that was done in plot #3 is not necessarily reflective of the entirety park, or even all of plot 3. Only one plot was done over the whole plot, and soils can vary greatly over a short distance.

What It Means:

The nature of the soils that were found in our soil pit had a surprising about of clay in them. This is promising for the forest, because soils with lots of clay in them of very good for drainage of water and storage of water. This is because clay is an extremely small particle and it can create secondary particles, or aggregates. These aggregates are smaller particles that are bound together to create bigger particles, which creates habitats for microorganisms and space to store, or drain out water. The only problem with clay soils is that it has a higher permanent wilting point than other soils. This means that although there might be the same amount of water put into the substrate as a sandy soil, the plant will have to put more energy into suction in order to get the necessary amount of water needed.

A map of different soil types in Niquette Bay State park

This map was made through the USDA Web Soil Survey. This program allows the user to specify a place using  coordinates or a state county, and the data base shows the user what the recorded soil types are in the area. This is helpful, because without taking a lot of soil samples, or even visiting a place, one can determine the most likely species of vegetation that would or could live in the area. 

The graph below shows the trend and change of particle texture as one goes down in soil horizons. When looking at this graph, one can see that as the soils get closer to the bed rock and surficial geology, the soil types have higher percentages of clay, and have a smoother texture.

This graph shows the trend of texture, as one goes down in horizons on plot #3