Passumpsic River - Geology

Geology

The Passumpsic Valley esker is the longest in Vermont and New Hampshire, if not in all of New England. It extends from St. Johnsbury northward past Lyndonville, where it splits into two branches, one extending up the valley of the Sutton River to West Burke and the other extending on up the Passumpsic River valley to East Haven. In some places it is over 150 feet (46 m) thick and two or three hundred feet wide.

Based on research by Edward Hitchcock two or three basins can be identified based on a larger number of interconnected terraces in the Passumpsic River Valley.

The first extends from the mouth of the Passumpsic River in Barnet, to the northwest corner of the town of Waterford, on the railroad. It is about 4 miles (6.4 km) long. The river runs through a narrow valley in Barnet, a gorge with no terraces. Narrow terraces in the Town of Passumpsic expand and form a basin. The fourth terrace on the west side of the river is part of the next basin, which is in St. Johnsbury and Lyndon. St. Johnsbury Village is on this high terrace which is called "St. Johnsbury Plain". The base of the terraces at St. Johnsbury is composed of clay. The same terrace occurs on both sides of the river valley beyond Lyndon. There are lower terraces at intervals.

Lyndonville has a high terrace. This may have once extended across the valley to form the end of a basin. Its lower strata are clayey, and are folded and curved. West of this terrace the level is lower. There is the course of a former river bed which ran towards the east. At the upper village of Lyndon the first terrace is about 1 mile (1.6 km) wide. There is a lot of sand and fine gravel adjoining.

Every stream from either side of the valley has its large terraces to correspond with those of the Passumpsic River. It is a characteristic of these terraces that they are large while their quantity is small. The count never exceeds five which is unusual.

The third basin includes the east branch of the Passumpsic River which runs through the Town of Burke. In East Burke there are several terraces. Near the village there are four on the west side, and two on the east side. Above East Burke the valley rises so that its bottom appears like a terrace. Its steep slope crosses the valley at right angles. There are indistinct terraces on its sides. Since the valley seems to be too wide to correspond with the size of the river, the valley may have been formed by water from unknown sources in prehistoric times.