Gettin' Down to the Nitty-Gritty

Last Tuesday, we visited our site to analyze the ground beneath it, from the bedrock to the organic layer. Although there are no bedrock outcroppings on our site and we didn't dig deep enough to find it, geologic maps of Vermont show that our site stands on the Monkton Quartzite formation. Quartzite is a metamorphic rock formed when sandstone (a product of sand and feldspar, the two most common minerals found on Earth) is subjected to intense pressure and heat as it is subducted under other layers of rock (Frank). This indicates that the rock under our site was near the shore of a shallow ocean or lake at some point in its history, which corroborates theories indicating that all of Vermont was once underneath the Iapetus Ocean.

More recently, when the geology and landscape of New England looked more as it does today, glaciers covered most of the region, and as these glaciers melted, they formed a freshwater body known as Lake Vermont, which covered most of the state. Our site was probably again on the edge or in a delta of this body of water, where the sand that sits atop the bedrock today settled out from the rivers that had flowed through the mountains. Further sand sediments may have been added when the shores of the Champlain Sea rested over our site. Starting about 10,000 years ago, the Champlain Sea receded and the waters between Vermont and New York became less brackish, giving rise to the modern-day Lake Champlain and allowing our site to become a floodplain where the Green Mountains drain into the lake, dropping loamy sediments that made the soil extremely fertile for the farming purposes of some of the Allens, who eventually settled here.

The map below (Poleman) shows the bedrock geology of the entire park as well as the surficial sediments under our site. To the west, the park is underlain by the Dunham Dolostone formation; to the west, Monkton Quartzite. On top of that, a layer of sand shows where the waters of the Champlain Sea lapped the shoreline.

Sources

Frank, Andy.  Quartzite.  Chemeketa Community College geology website.  Retrieved 20 Nov 2011 from .

Poleman, Walter.  Bedrock Geology of Niquette Bay State Park, Colchester, VT.  Map.  Obtained by personal communication.

Thompson, E. and Sorenson, E.  Wetland, Woodland, Wildland.  Hanover: University Press of New England, 2000.

Soil Horizons

Above, you can see our pile of soil, now determined to be Hinesburg Fine Sandy Loam from examining a surficial geology map, as well as some samples of the different layers in the cupcake tin next to it. Notice the different colors of each horizon- the O horizon is a rich, dark brown while the C layer at the bottom of our pit is orange because it is so highly oxidized. All of the layers are fairly sandy, with some loam to help retain water that percolates through.

Photo by Sam Smith

Substrate Analysis

This past week we did a substrate analysis of the soil on our plot. As you can see in the image above left, we dug a soil pit about a foot and a half deep and lined it with pegs to differentiate between the different horizons in the soil. The top two layers, the O (+3in.) and A (-4in.), are darkest due to high content of organic material, and have roots visible from the expansive field of horsetails throughout our plot. The B horizon, a mineral soil composed of loamy sand, extends another 10 in. below the A horizon (-14in.). Below 14 in., the soil becomes completely sandy in the C horizon, which extends an indeterminate depth to the quartzite bedrock.

We also did a pH test of our soil (above, right) and found it to be about 6.5. The lower pH implies that there is a higher concentration of H+ ions in the soil and low levels of calcium and magnesium. Although this is on the acidic side, the O horizon was rich and well developed which might explain how the Allen family was able to farm here.

Photos by Sam Smith

In this image of our soil pit, you can see both the O and A horizon dug so far. The O horizon measured about +3 inches (7.62 cm) and the A horizon was -8 inches (20.32 cm). Both horizons have roots from the numerous horsetails visible.

Photo by Sam Smith

Our first blog post!

We've laid out the boundary of our 1-hectare plot and created a basemap, including sites of the homestead buildings and the well. Below is a Google Map showing our site relative to the rest of

the park. We've also broken down the plot by different stands of vegetation, calculating the area of each stand in Google Earth to create this pie chart below.

Here are some links to KML maps (viewable in Google Earth) that show the approximate cover areas of our different vegetation types:

Site 5 Plot Boundaries

Canopy

Horsetail Understory
Vernal Pools

View Niquette Bay State Park, VT--Allen Homestead in a larger map

On another note, we have also unearthed a more creative map of our site that indicates a large treasure buried in the well on our site during the mid 1800s when pirates ruled the depths of the lake. It also highlights another safe area to hide stolen loot, and the unexplored territory up near what is now Raymond Road and Rt. 2. We have yet to locate the treasure, but maybe one of you will!

Sources:

Basemap by Sam Smith, Ryan Tessier, Darren Schibler
Template for Pirate Map: 20-20 Template Site. 2011 LoveToKnow Corp