As a member of the Opacum Land Trust, I was invited to a guided walk this morning at the Claire Birtz Sanctuary in Southbridge, a 116 acre property on the west side of Route 169 and very near the Connecticut border.  Opacum Board member Alan Smith led a small group of us on a two hour hike: we started off on the Blue Trail, picked up the Yellow Trail, bushwhacked for a bit to the property line, and then returned to the parking area via the Blue Trail again.

The walk description promised us “a historical journey through the past use of this interesting property” as well as a discussion of natural features such as vernal pools.  A geologist and archaeologist, Al impressed us with his wealth of knowledge.  I wanted to soak in the atmosphere and enjoy myself, so I only scribbled down a few notes.  The following are more or less random observations, but they are what I found striking and worth recording, organized into four groups.

Geology

New England’s current landscape is glacially formed.  The retreat of the ice sheets during the most recent glacial period, the Wisconsin, occurred 12,000-15,000 years ago.  Landforms like drumlins and kettle ponds, common in New England, were formed when the glaciers receded.

Prior to the glaciation events, back in the distant past — in fact, 365-425 million years ago — this area experienced the Acadian orogeny, which was the third of the four orogenies that created the Appalachian Mountain chain.

These mountain-building events can be inferred from tilted planes of rock which we see on this property and at numerous nearby sites; these are evidence of thrust faulting.

Rocks in the Southbridge area are often granite (igneous) or granitic gneiss (metamorphic).

A glacial erratic is composed of rock that differs from the surrounding substrate, whereas a glacial boulder is a rock like all the other rocks around it, only bigger.

Scientists estimate that the Earth is about 4.5 billion years old, but the oldest rocks in Massachusetts are only about a billion years old (due to extensive mountain building events which recycle and reform the Earth’s crust); these rocks from the Grenville orogeny, dated to about 1.2 billion years ago, can be found in the Berkshire highlands.

Archaeology and Human Habitation

Native Americans used waterways as roads; rivers and streams were their transportation corridors.  The pictures we have in our heads of Algonquian tribes paddling around in their birchbark canoes have a basis in fact.

Colonists who built stone walls used the materials they found to hand: blocky, rectangular stones from the mountain-building episodes and rounded stones sculpted into that shape by glacial action and running water.  You can see both types in this section of wall:

The shallow depression we saw near the property boundary line could be a cellar hole, but it could also have been a Native American sweat lodge.

In the mid-eighteenth century, when Native Americans were losing their land to settlers, they often lived “under the radar” so to speak; in the colonial era, they might have worked at the Sturbridge Lead Mine, but they also continued observing traditional practices to the extent that they could.  This stone structure could have served a religious or ceremonial purpose:

A common system for classifying soils defines distinct strata by their color and composition, as well as inclusions: A-dark, B-yellow, C-light yellow, then bedrock underneath.

Flora

Spicebush (Lindera benzoin) grows in rich soil; its tiny yellow flowers appear in early spring and red drupes (berries) in the fall.

Witch Hazel (Hamamelis virginiana) is used medicinally.

Ferns (Cinnamon, Interrupted, Christmas, and more!) are common in the understory.

Mountain Laurel (Kalmia latifolia) blooms in early summer.

Groundnuts (Apios americana) are edible and, although not cultivated, were used as a food source by the early colonists.

Maple Leaf Viburnum (Viburnum acerifolium) has leaves which look like maple leaves, but this plant is a vine, not a tree.

Plane trees (genus Platanus) are native to the northern hemisphere; their leaves may look like maple leaves, but this is a different genus; there are fossil records of plane trees from as far back as 115 million years ago.

The Cattail Swamp, adjacent to Morse Pond, is a prominent feature of the sanctuary.  The cattail (Typha latifolia) is a versatile plant for human use: the rhizomes can be ground into flour; the stems can be cooked; the leaves are edible, as are flowerheads; the fluff can be used to line moccasins or for bedding.

Fauna

Intermittent streams are home to salamanders.

Certified vernal pools do not have fish in them; instead they harbor species like frogs and fairy shrimp.  It’s hard to see in this photo, but this is a vernal pool:

Garter snakes are harmless and should be left alone:

At the end of the walk, Al offered to lead the group to the remains of a nineteenth century mill dam nearby, but I had another engagement on my calendar and had to hurry on home.