State Route 9 Interchange 13 - Beaver Meadow Road, Haddam, Middlesex County, Connecticut, USAi

Regional Level Types
State Route 9 Interchange 13 - Beaver Meadow Road	Road Cutting (Inactive)
Haddam	Town
Middlesex County	County
Connecticut	State
USA	Country

The state Route 9 divided, 4-lane expressway cuts diagonally through the metamorphic rocks of south-central Connecticut. In central Haddam, where Route 9 trends NW-SE, interchange 13 (formerly interchange 8 until mid-2023) connects it with Beaver Meadow Road, which crosses it at nearly a right angle. This interchange was opened in 1969, the reference coordinates for its center are given below.

Extensive and deep roadcuts along both sides of the divided highway, along the on and off-ramps, and on nearby Hubbard Road have exposed rock units of the Middletown Formation, a metamorphic sequence consisting mostly of amphibolite, orthoamphibole gneiss, and biotite gneiss. Lundgren (1979) provides a detailed map and description of the rock units and their mineralogy at this interchange. Most of the minerals mentioned are rock-forming grains, but he notes one distinctive unit, “A gneiss in which gedrite occurs in well aligned prisms and in conspicuous rosettes of prisms. This unit also contains cordierite. It is well displayed in the cut on Hubbard Road at Beaver Meadow Road, the entrance to the northbound lane of Route 9, and in the exit from the southbound lane of Route 9 at Beaver Meadow Road”.

Bannerman, Quarrier, and Schooner (1968) gave the following descriptions of minerals at the roadcuts:



Gedrite has been mineralogically redefined since 1979, so the amphibole there is now probably anthophyllite. A specific 2016 microprobe analysis identified the "gedrite" as "anthophyllite", which is widespread in the Middletown Formation.

Hiller (1971) also noted bavenite at the "small pegmatite body" described above. This bavenite was described by Henderson (1970), which was "found in or close to hexagonal cavities after beryl or cavities still partially filled by corroded beryl crystals. Only small amounts of unaltered beryl were found." He noted one "single superb specimen of bavenite was found consisting of crystals so large that they have the pale apple green color of prehnite. The crystals comprise five fans on albite with black tourmaline. Each crystal is about 4 mm square by 0.2 mm thick".

Yedlin (1967) mentions a chlorite schist from a now lost location between this pegmatite and Beaver Meadow Road that produced many sharp edged, doubly-terminated, nearly perfectly trigonal, black tourmaline crystals. One of these is drawn on the cover of Hiller (1971). These were common in old collections, but usually were just labeled as "Haddam" or incorrectly as coming from Tim's Hill.

An extensive blasted rock dump is present up to 0.5 km NNW of the interchange, in the area between Route 9 and Hubbard Road. Some of the minerals described have been found there as well, particularly large boulders of the gray, anthophyllite prism-bearing, granular quartz gneiss. This area was sold off by the state and developed into residential lots circa 2007.

Other Regions, Features and Areas containing this locality

References