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Local Geologic History Mystery Solved.
By Glenn Kreisberg While walking with the kids down by the Sawkill off Chestnut Hill Road a few weeks back, my wife Stephanie came across an interesting stone. It looked like your typical slightly oval, river rounded, brown piece of sandstone except one side was smooth faced with a thin layer of shiny, white quartzite like rock attached to the sandstone. It was quite beautiful to look at and silky smooth to the touch compared to the rest of the courser sandstone of the rock.
We placed the found item on the chimney mantel where it sat until last Friday. At that time I was heading up to the State Museum in Albany to photograph artifacts from their anthropological collection as part of an ongoing project for the New England Antiquities Research Association (NEARA). I grabbed the stone on my way out the door thinking perhaps I could get a state geologist to take a look and offer an opinion.
Arriving at the museum I showed the rock to our project liaison, Archaeology Collections Technician and native New Zealander Ralph Rataul, and asked if a geologist might be available to inspect the item. Ralph, the infectiously enthusiastic guy that he is, said “absolutely”. A few minutes later and we were in the lab of New York State Chief Geologist, William Kelly.
Kelly’s interest seemed immediately piqued. His first reaction was puzzlement saying he had never seen anything quite like it before and that alone made it unusual and interesting to him. With some chipping and probing he quickly determined the sandstone, with small flakes of quartz, feldspar and clay present, was not native Catskill sandstone. So, he said, it could be depositional having been carried and dropped from someplace else, perhaps by a glacier.
But there was a greater mystery here. The thin layer of shiny white material with a slight bluish-green tint, which Kelly said resembled an Opalate or Agate type of quartzite, was anomalous. This is what he had not seen before, at least not in this form. After examining the object under a microscope and identifying an “odd” thin black layer between the shiny surface and the rock beneath, Kelly picked up his phone and called for a second geologist to assist with the examination. I must admit, at this point, excitement was building and Ralph the collections technician said not much fazed these guys when it comes to rocks. Clearly, these state geologists had a determination to discover for themselves what this object was.
Soon after the second geologist examined the rock a discussion ensued between the two scientists as to whether this object was natural or manmade. It had never occurred to me that this could have been anything but natural. Bill was of the opinion the object was possibly man made (probably because he had never seen anything like it before). His colleague Mike Hawkins was of the opinion it was, in fact, natural. It suddenly seemed we were engaged in a game of stump the geologists.
It was time to breakout the big guns; a larger more sophisticated microscope was employed, one which used polarized lens filters to determine the refractive light properties of a sample. This would be used to determine if the thin shiny layer was in fact quartz crystal.
A sample of the “quartz” layer was chipped off the rock. The small chip was first ground up and then pulverized in preparation of the sample being placed on a slide. But before the sample was placed on the slide it was mixed with some oil that would only allow light to pass through the sample if certain elements were present. From a tray of some several dozen oils, each corresponding to a different element such as silicon or carbon, the one that corresponded to quartz was utilized. If the molecular structure of the oil and that of the powdered sample aligned, light would shine right on through the sample on the slide. If the sample were not quartzite based, the light would be blocked. In a few moments we had our answer: The sample was not quartz. In fact, it was determined that the sample was actually glass.
At this point I think I said something like, “Oh, that’s very interesting because a few miles upstream from where my wife found the stone a glass factory once stood a couple hundred years ago.” …To which the Bill Kelly, Chief NY State Geologist, said something like…”Oh sure, now you tell me that.”
Now, armed with all the clues needed to make a truly scientific determination, the story of this man made artifact began to become clear. And it went something like this: The stream tumbled fist sized oval “rock” began as a rectangular clay and sandstone brick, a brick from a wood fired glass kiln used at an early glass factory in Woodstock. It was speculated that while the kiln was being fired some of the glass products melted against the inside wall of the brick kiln and that some of that glass fused to the brick. When it cooled, the glass appeared as a shiny, thin glassy layer along one side of the brick.
When the glass industry in Woodstock came to an end and the kilns were disassembled, some of the discarded kiln bricks found their way in to the nearby stream which feeds the Sawkill. Nearly two hundred years of water flow later and the remnant of the kiln brick had tumbled down stream about three to four miles to the spot near the stream off Chestnut Hill Road where my wife found it lying.
 Photo by Stephanie Kreisberg Legacy of the Woodstock Glass Works
As many locals know, beginning in 1809 and running through the middle of the 19th century, Woodstock was home to five glass factories: all testaments to early American industry, commerce and ingenuity. The largest of these, the Bristol Glass, Cotton and Clay Company, operated in the Hamlet of Bristol which is now known as Shady. Another glass settlement was located on the lower slopes of Indian Head Mountain opposite the MacDaniel farm on MacDaniel Road. This location was closer to the hemlock groves that were cut down to fire the kilns used by the glass factories.
Little if anything remains of this enterprise, which at its height involved over 40 families and recruited specialized craftsmen including Flemish glass blowers from Europe. Interestingly, some European countries enacted laws preventing such workers from emigrating to the U.S. during this period, as it was against their national interests to lose such skilled and valued artisans.
It’s said that if you hike to the area on the lower slopes of Indian Head Mountain where the glass works and settlement once stood, you can still find evidence of the operation in the form of small glass pieces scattered and in piles. Also interestingly, the highly prized and sought after Woodstock glass products often took on a greenish blue tint which was also present in the kiln brick artifact that was found. Yet more confirmation that the story of this found object was now known and could be told.
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