Aggregates Manager Digital Magazine
Issue link: http://read.dmtmag.com/i/468886
AGGREGATES MANAGER March 2015 40 by Bill Langer Bill Langer is a consulting research geologist who spent 41 years with the U.S. Geological Survey before starting his own business. He can be reached at Bill_Langer@hotmail.com "There sits a stone-mason... His hammer, his chisels, his wedges, his shims or half-rounds, his iron spoon — I suspect that these tools are hoary with age as with granite dust… His work is slow and expensive. Nature is here hard to over- come. He wears up one or two drills in splitting a single stone… He grows stony himself. His tread is ponderous and steady like the fall of a rock. And yet by patience and art, he splits a stone as surely as the carpenter or woodcutter a log. So much time and perseverance will accomplish. The Journals of Henry David Thoreau. Sept. 11, 1851 Circa 1814, the first quarry in Barre, Vt., opened on Cobble Hill. Quarrying was a very physically demanding job, and sometimes nature, as Thoreau said, was very hard to overcome. This was especially the case just a few years after the quarry opened. Quarriers commonly worked three seasons of the year, but not always. Dur- ing 1816, it was 90 degrees on June 5. The following day, the temperature dropped to 40 degrees. It began to snow and did not stop until June 10. It was so cold that, for five nights in succession, it froze as hard as it usually did in December. By June 10, there was about a foot of snow on the ground. The rest of the summer was not much better. Temperatures were well below average. Furthermore, although some parts of New England got rain, Vermont was bone dry and, by summer's end, had gone a full three months without rain. Fires swept through parched forest land and filled the air with acrid smoke and a general darkness. The adverse weather was a result of a natural catastrophe that occurred a year earlier nearly half way around the globe. On April 10, 1815, Mount Tambora, a volcano in Indonesia, erupted with more force than any volcano in recorded history. Along with a cloud of dust, ash, and cinders, 60 megatons of sulfur were ejected into the atmosphere resulting in the drastically lowered temperatures during what became known as 'the year without a summer.' Try as she might, Mother Nature could not hamper the Barre granite industry. New quarries opened up on Cobble Hill and nearby Millstone Hill. All the quarries were located in the 380- to 330-million-year-old Barre pluton, which is a large body of igneous rock that solidified deep within the earth. Eventually, the pluton was exposed at the land surface through the forces of plate tectonics and erosion. The Barre Pluton is huge — about 4 1/2 miles long, 2 miles wide, and 10 miles deep. The granite in the pluton can be light to dark in color depending on the mineralogy of the rock. Quartz and feldspars are the chief light-colored minerals, and biotite is the prevalent dark-colored mineral. The amount of biotite primarily is responsible for the color. The year following 'eighteen-hundred-and-nearly-froze-to-death,' a contract was issued for the construction of a courthouse in Montpelier, the state capitol. The contract stated there were to be "three door steps twelve feet long and hewed of Barre ledge stones." Technically speaking, the Barre Pluton is a fine- to medium-grained granodiorite, but, even among geologists, the rock com- monly is called 'Barre granite.' Imagine someone referring to the world famous Barre Granite simply as 'Barre ledge stone.' Blasphemy! Vermont granite miners survived their early days despite a year without a summer. THE BARRE LEDGE Stone The eruption of Mount Tambora was 100 times more powerful than the eruption of Mount St. Helens, shown in this figure.