|Advancing Vermont Malacology|
|Finding lime recycled after half a billion years of mineral inertia (updated 9/11/04)|
|By Harry G. Lee|
| My wife's birthday occasioned a visit to her family's
"Homestead" just north of Manchester Center, Bennington County, Vermont over the
weekend of September 26-28, 2003.
Aside from the indoor and patio festivities, the two dozen or so visitors enjoyed an assortment of outdoor recreation ranging from jogging, hiking, and fly-fishing to pet burial, fence-dismantling, and, needless to say for the honoree's spouse, prospecting for shells.
|Mt. Equinox, Vermont|
|photograph by Suzie Lawrence|
The Homestead is located in the valley of the fabled trout stream, the Batten Kill, as it winds its way to the Hudson River between mountain ranges. Two crests dominate the western horizon: Mt. Equinox (highest point 3848 feet above sea level) in the SW and a lower ridge also belonging to theTaconic Mts. (Mt. Aeolus, Owls Head, Netop and Dorset Mt.) to the NW. On the second day, when the mist had risen high enough in the morning sky, I was able to make out a bare whitish scarp on the north flank of Mt. Aeolus, which rises about 2400 feet. I inquired about this feature, and my mother- and brother-in law confirmed my suspicion that this was a marble quarry - one of a group of two dozen excavations on the slopes of Dorset Mountain and Mt. Aeolus.
|Dorset marble mining operation|
quarries began as America's first commercial marble industry. Mining was
begun in neighboring South Dorset by Isaac Underhill in 1785 and
flourished for some 130 years. Dorset marble, as this deposit came to be
called, built the largest marble structure in the U.S., the New York
Public Library, as well as the library of Brown University and Memorial
Continental Hall of the Daughters of the American Revolution in
Washington, D.C. It was also used for over 5000 headstones over the
fallen soldiers at the battle of Gettysburg.
I recalled that the principal stuff of marble, calcium carbonate, is the mineral terrestrial snails (just as marine and aquatic ones) use to fashion their shells; consequently these mollusks tend to prosper in habitats on or very near exposures of this rock. Furthermore, after the demise of their inhabitants, the empty shells persist in situ far longer due to the buffering of acidic groundwater that etches and ultimately dissolves their mineral content. Thus collecting is easy and usually profitable. With geographic guidance from brother-in-law, Hamilton "Ham" Hadden III, and the company of Ed Cavin (Jacksonville, FL), I set out by car to approach the point on the mountainside we had observed from the patio of the Homestead. This being a well-contrived collecting trip, our expectations were high. Yet, as we all know, too much scheming can be a recipe for failure, so our prospects were tempered with various practicalities such as our fitness for the ultimate assault of the mountain by foot.
First a word about American landsnails, and those of Vermont in particular. It is apparent that the state has never been a popular destination for snail-collectors, and very little has appeared in the literature about its molluscan fauna. Most references are in the form of simple locality-citations in a variety of works with a far wider geographic scope or in phylogenetically-restricted studies. In the nineteenth century Charles Baker Adams (1814-1853)* wrote a few short papers on the state's fauna during his tenure at Middlebury College (1838-1848) including the years he was the head of the Vermont Geological Survey (1845-1848). Monographic treatments of the non-marine mollusca of the other New England states have appeared in the literature over the last century and a half, but nothing of that scope has been dedicated to the malacofauna of Vermont.
As a student at Williams College, just over the Massachusetts
line, an hour to the south, I wrote my senior honors thesis (unpublished)
entitled The biology of the testaceous Mollusca of the Williamstown area.
It included reports of three 1961 collecting expeditions to the vicinity of
Pownal, a Vermont town several miles south of Manchester but also in Bennington
Co. One of these three stations was an abandoned marble quarry! A total of 25
species was collected, and we will see below how this assemblage relates to the
efforts in the neighborhood of the Homestead.
Getting back to the Mt. Aeolus marble quarry expedition.... After being escorted by "Ham" to the trailhead, we debarked afoot and made a 45 minute ascent of the mountain with moderate effort. After passing through a forest of hemlock, birch, beech, and maple on an unusually straight and commodious trail, we came in sight of the areas of exposed marble, and I paused to reflect on what I knew of this formation. It started as limey mud formed by long extinct invertebrates as they died and sank to the bottom of a shallow Cambrian sea about 463,000,000 years ago. Later, additional sediments and collisions between continental plates applied pressure and heat to these limey strata - metamorphosing limestone to marble. Here we were at the end of our ascent, and Ed and I immediately noticed empty snail shells for the first time on the trek. After about a half-hour of our visual reconnaissance and hand-picking of about five dozen shells (figure 1) of about ten species, I scooped up several handfuls of the humus in the rock crevices and stashed them in a one quart ziplock bag. This stuff was later dried, sifted, and sorted under the microscope and, mirabile dictu, nearly a hundred more shells were culled. The total species count was a fairly astounding 23. The list follows (phylogenetic order; scientific name, author, date of description, official vernacular name;** typeface in green indicates a new county record; new state records are indented):