Geological Society of America Centennial Field Guide Northeastern Section 1987 Barre granite quarries Barre Vermont Dorothy A Richter Hager Richter Geoscience Inc P O Box 572 Windham New Hampshire 03087 LOCATION Wells Lamson Quarry Company Both companies are accommodating to serious visitors and researchers who wish to do detailed sampling or mapping The Pirie Adam Smith and Wetmore Morse quarries are especially interesting to visit There are more than 70 inactive quarries in the Barre area but most are now filled with water in fact many are a part of the local public water supply Dale 1923 provided a map showing the locations and names of many of the quarries active at that time The Barre granite quarry district is located in the southeastern section of Barre Town Washington County Vermont near the villages of Graniteville and Websterville The quarried area extends slightly into the northeastern corner of Williamstown Orange County Figure 1 shows the general location of the quarry district and the various village entities within Barre Town From I 89 the area is reached by taking Exit 6 Barre South Barre and following the access road 5 mi 8 km to the intersection with Vermont 14 Fig 1 Cross Vermont 14 and follow Middle Road to Graniteville Figure 2 shows the locations of the quarries discussed in this field guide Public viewing platforms are available at the edge of the Rock of Ages quarry behind the Rock of Ages Visitors Center 0 9 mi 1 5 km east of Lower Graniteville and the Wells Lamson quarry along the Websterville Road at the north end of the quarry During the summer months Rock of Ages operates a short train ride for tourists that gives an excellent view of the active Smith Quarry and the abandoned Duffee Quarry Access to the several other active and abandoned granite quarries in the area may be obtained only by making prior arrangements with the Rock of Ages Corporation and the SIGNIFICANCE The Barre granite quarries expose a three dimensional view of a small well studied pluton of the New Hampshire Plutonic Series It is a Devonian talc alkaline pluton formed by partial melting of Siluro Devonian sedimentary rocks that had been folded and regionally metamorphosed during the Acadian orogeny and thus illustrates that the orogeny occurred rather suddenly in the region Contact relations with the Siluro Devonian Gile Mountain Formation internal igneous flow features and various types of postconsolidation fracturing are very well displayed in the quarries In addition the Barre quarry district is one of the few localities in the Northeast U S where geologists and the public can observe the ancient and honorable tradition of quarrying largedimension stone blocks REGIONAL SETTING Figure 1 Location of Barre quarry district and numerous villages within the boundaries of Barre Town Vermont The Connecticut Valley Gasp synclinorium in eastern Vermont is characterized by tightly folded phyllitic and calcareous metasediments of the Gile Mountain and Waits River formations The metasediments are generally interpreted to have been deposited in the remnants of the Iapetus ocean A series of more than 20 two feldspar two mica granitoids ranging in size from small dikes 0 6 mi 1 km long to plutons 37 mi 60 km in diameter intrude the metasediments in eastern Vermont In general the plutons are unzoned internally uniform in composition and not associated with igneous rocks more mafic in composition than diorite Contacts with the metasediments are mildly to strongly discordant Metamorphic aureoles are associated with most of the intrusions including the Barre pluton indicating that the plutons were intruded after the peak of regional metamorphism The regional metamorphic grade of the host metasediments ranges from garnet to kyanite grade in central Vermont The regional metamorphic grade around the Barre pluton is staurolite grade Naylor 1971 obtained K Ar dates on primary micas in 239 240 D A Richter Formation for a segment of the eastern contact A much larger igneous body of similar composition the Knox Mountain pluton occurs a few miles northeast of the Barre pluton The Gile Mountain Formation is composed of fine grained dark gray mica schists and micaceous quartzites The Waits River Formation contains similar rocks plus abundant caleareous schists The stratigraphic relationships between the two host formations are complex and contradictory in places Woodland 1977 and Fisher and Karabinos 1980 determined from structural analysis and graded bedding in the Royalton area approximately 31 mi 50 km south of Barre that the Gile Mountain Formation is younger than the Waits River Formation and that the belt of Gile Mountain Formation in which most of the Barre pluton resides is the core of a north plunging synform Woodland 1977 has further suggested that the synform is the downwardfacing nose of a recumbent nappe with an eastward root zone Contacts of the Pluton Foliation of the metasediments near the Barre pluton is nearly vertical strikes north northeast and more or less bulges around the igneous rock The contacts of the pluton are thus semiconcordant with the foliation in most places It appears that the pluton gently shouldered itself into position along zones of weakness in the country rock Large xenoliths 6 ft or 2 m that appear not to have been reoriented are common and septa of the metasediments possible roof pendants are present within the pluton A good pavement exposure of the contact occurs behind the storage garages at the south end of the Pirie quarry The contact is exposed in places along the east walls of the Rock of Ages and Pirie quarries where quarrying terminated A large septum of the Gile Mountain Formation roughly follows the road between Lower Graniteville and Websterville Small outcrops along the road contain the contact and small dikes of granitic material invading the country rock Contact with the same septum is visible along the east walls of the Smith Wetmore Morse and Wells Lamson quarries Figure 2 Sketch map showing quarry locations discussed in text Composition several of the Vermont granitoids including the Barre pluton that clustered around 380 Ma He concluded that the Acadian erogenic event in that part of the northern Appalachians must have been a brief but intense event since the Devonian granitoids crosscut Devonian sediments that had been folded and regionally metamorphosed before intrusion BARRE AREA Figure 3 is a generalized geologic map of the Barre area modified