Flynt Quarry Monson, Massachusetts

A Report on the Quarrying Technology and Techniques Used at the Flynt Quarry Site

By James Gage

Copyright

Copyright © 2010. James E. Gage. All Rights Reserved. This document may be circulated and reproduced for educational purposes.

Credits

Unless otherwise noted the photographs are by James Gage Figures 8 & 12 courtesy of Stephen Phillips, used with permission.

Cover – Flynt Quarry circa 1910, courtesy of the USGS

Contact

James Gage 163 Kimball Road

Amesbury, MA 01913 info@stonestructures.org

Notes

This document is a brief review of the major points of interest from the April 15, 2010 tour of the Flynt Quarry Site in Monson Massachusetts.

Report issued May 15, 2010

Figure 1 – Excerpt from 1946 USGS Map showing the two quarry pits in floor of the quarry.

Flynt Quarry, Monson, MA – By James Gage

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Quarry

The Flynt Quarry is situated on the lower slope of Bunyan Mountain on the southwest side. It is on Margaret Street formerly known as Granite Road. The quarry was opened in 1825 and ceased operations in 1935. The quarry was worked by cutting into the hillside and removing the stone in stepped horizontal layers. This was made possible by the presence of high quality stone near the surface, a highly unusual situation. Most commercial quarries needed to cut deep into the bedrock to find high quality stone. Cutting into the hillside rather than cutting a deep pit had a significant economic advantage. The Flynt Quarry drained any accumulated ground water by utilizing the existing natural slope of the quarry floor. Deep pit quarries required constant mechanical pumping of the water to keep them dry. This added expense to the quarry operations.

Figure 2 – A photograph showing how the layers of stone were removed in “steps.” The dark color stone on the left is an intrusive dike. The lighter colored stone is the granite / gneiss being quarried.

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Figure 3 – Six pointed star drill hole

Figure 4 – Five pointed star drill hole

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At some point after 1908 and prior to 19351, the Flynt Quarry opened two pits in the floor of the quarry (fig.1). This seems to have been in response to the high quality stone being nearly exhausted in the hillside. The northern face wall of the quarry shows signs that the high quality stone was playing out. Intrusive dikes of other types of rock are evident. There is extensive evidence of blasting of the north face wall to remove poor quality and intrusive rocks. Exploratory trenches are also in evidence just above the north and east face walls. Exploratory trenches were done to assess the quality of stone before extending the quarrying in that particular direction. This suggests there were concerns about the quality of the stone in those areas.

The two pits and the floor of the quarry were used as a landfill by the Town of Monson and are no longer visible. Star Holes

The Flynt Quarry has the largest known collection of star drill holes. Star drill holes are scarce to rare and only a handful of examples have been previously reported.2

A star hole has five or six rounded points around the circumference of the drill hole. (figs. 3 & 4) It is similar in shape to the * symbol. The rounded channels that form the points can (1) extend vertical up and down the hole in a straight line, or (2) the channels can slowly rotate in the hole creating a rifled hole similar to the rifling found inside a gun barrel. (fig.5) All of the Flynt Quarry examples are rifled. Only a portion of the entire length of the drill hole will exhibit star hole characteristics. The remainder of the hole will be rounded. The rifled star section can form at any point along the length of the hole. The length of the rifled section can range from less than 1 foot to several feet.

Star holes are the result of a standard quarry drill bit used to drill round holes “chattering” during the drilling process. Chattering refers to the drill bit bouncing around inside the hole. Preliminary measurements at Flynt Quarry indicate the star holes are as much as a ! inch wider in diameter than the drill bit used to drill the hole. This additional ! inch of width was most likely the result of the drill bit chattering in the hole. Figure 5 – Close-up showing the five channels rotating counter-clockwise creating a rifling effect inside the hole.

1 Two pits are shown the 1946 USGS map (see fig.12) but not on the 1908 USGS map. 2 A single star hole in a breakwater in Rye, NH, a single hole from Cape Cod, single hole from southwestern Rhode Island, and unknown number of examples from the Hoosac Tunnel in western Massachusetts.

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Blasting

The blast holes at the Flynt Quarry come in two diameter sizes: 1" inches and 2 inches. Most of the blast holes range from 40 to 56 inches deep and were spaced several feet apart from each other. The spacing varied to accommodate the type of rock being blasted, the purpose of the blast, and other factors.

Figure 6 – Typical blast holes found at the Flynt Quarry

In blasting, only a portion of the hole was filled with black powder. The remainder of the hole was filled with stone dust, clay, sand, or other inert material. The fuse was passed through the inert material into the powder and the holes blasted. This method of blasting concentrated the force of the blast in the lower section of the hole. The lower sections are generally heavily damaged by the blast but the top sections are sometimes unharmed and remain intact. Examples of this are common at the quarry. (fig.7)

Blasting at the Flynt Quarry (based upon the surviving evidence) was used to remove intrusive dikes of rock, break up poor grades of granite and gneiss for the rock crushing operation, and was also used experimentally in the white gneiss section of the quarry in the south eastern corner of the site. The white gneiss section shows extensive evidence of quarrying problems. There is evidence of experimentation with different methods for splitting this rock. Blasting was one of those experimental methods.

Figure 7 – Blasted hole showing the upper section unharmed by blast.

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Quarrying Problems Throughout the quarry, there is evidence that that quarrymen were having difficulties getting a clean straight vertical split in the rock. The quarrymen adopted a number of different strategies to address these problems. These solutions are discussed in the subsequent sections. The primary problem encountered at the Flynt Quarry was having the rock fail to split vertically up and down. The rock would sometimes split with a curved surface rather than a flat surface. This problem is evident in the white gneiss section of the quarry. A large curved split can be found in the middle of the quarry floor in this section (fig.8) Plug & Feather Method

The commercial version of the plug and feather method was the principle means of quarrying the stone at the Flynt Quarry. The typical plug and feather round drill holes at the quarry are " inch in diameter and an average of 3 inches deep. The holes are spaced from 3 to 6 inches apart along the line of the split. The spacing between the holes was dependent on the type of stone being quarried. The more difficult it was to obtain a clean split, the closer the holes were drilled. The northern section of the quarry had an average spacing of 4 inches between the holes. The eastern section had an average of 6 inches. The southeastern area with the white gneiss had spacing ranging from 2 to 3 inches between holes. (fig. 10)

The stone was split by inserting two half round shims called “feathers” with a wedge called a “plug” between them into each hole. The plugs were tapped with a mason’s hammer one after another along the line of the split. This was repeated until a cracking noise was heard and the stone split. Figure 9 shows a typical set of “plug and feathers”. A single example of the “plug and feathers” still in a block of stone was found in northeast section of quarry about 10 yards back from the top edge of the quarry face wall. (fig. 11)

Figure 9 – A set of “plug and feathers.” The plug or wedge is in the center and the two half round metal shims on either side are the “feathers.” (Author’s collection)

Figure 8 – A “Curved” Split Photo courtesy of Steven Phillips

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Figure 10 – Some types of stone like this white colored gneiss required the drill holes to be spaced closer together to achieve a clean split. In this example the holes were

spaced 3 inches apart.

Figure 11 – Plug and Feathers which got stuck in the rock when it failed to split.

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Foot-Holes In several places in the quarry, there is a line of typical short round drill holes with a deeper hole (as much as 12 inches deep) found every so many holes. These deeper holes were called “foot-holes” and were used to insure a more accurate split of the block along the intended path of cleavage. The date that this technique was first introduced is still under investigation.

Fig 12 – A line of short round holes with a deeper “foot hole” used to improved the accuracy of the split. The “foot hole” is indicated by the blue arrow.

Photo courtesy of Stephen Phillips Tracing Method

Another method used to improve the accuracy of splitting with the plug and feather method was to chisel a shallow groove along the length of the split. This method is called tracing. The scored line was cut using a mason’s cold chisel. One example of this method was found at the quarry. Surviving historic examples of this method are rare. This was an important find. This method was used as early as the 1750’s without drilled holes and predates the plug and feather method. Tracing is occasionally still used by stone masons today. (Fig. 13)

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Figure 13 – The chiseled line running from hole to hole was used to improve the accuracy of the split. This method is known as tracing. Examples of this method are rare.

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Broach Channeling Method (1885-1945)

Channeling refers to the process of cutting a continuous vertical channel on the left, right, and rear sides of a quarried block of stone to completely separate it from the bedrock. There are several different ways to cut the channel. With granite and gneiss, the typical approach was to drill a series of closely spaced large diameter holes along the length of the channel. Once the holes were drilled, the stone between the holes was broken away with a “broach bit” creating a continuous channel. Most of the channel drilling done with round holes is dated from after the introduction of steam and compressed air drills. The method was costly and time consuming. The only economical means of using this method was machine drilling rather than hand drilling. Examples of this method are only found in the white gneiss section of the quarrying. There are only a few examples of it suggesting it was being used experimentally. Broach channeling was first mentioned in the quarrying and mining literature in 1885 and the last references to it are in 1943. This gives a date range 1885-1945 for the technique. The largest concentration of references to this method is from 1890 to 1935. This represents the peak period of usage for this method.

Figure 14 – Example of broach channeling found in the white gneiss section of the quarry.

Derrick Anchor Points

Two types of anchor points were found for securing the steel cables for the derricks. One type was a round U-shape metal staple inserted into the bedrock. It was wedged tight in its holes with pieces of iron. The second type is a metal pin anchored to the bedrock at an angle. Only one example of the pin type anchor point was found (i.e. white gneiss section).

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Figure 15 – U shaped anchor point for derrick guy wires

Figure 16 – Pin type anchor point for derrick guy wires

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Dog Holes A dog hole is a shallow two to three inch diameter round hole drilled on the side of the stone block several inches below the top. On the opposite side of the block a second dog hole was drilled. The pair of dog holes allowed a pair of iron hooks to grab the stone block. The hooks were connected together by a chain. As the chain was lifted by the derrick, it tightened the hooks and allowed the block to be lifted safely. Only a single example of a dog hole was found at the quarry. This technique of lifting the stone blocks may not have used much at this quarry. Figure 17 – Typical example of a Dog Hole used for lifting stone blocks in the quarry. (This example is from Babson Quarry in Rockport, MA)

Figure 18 – This illustration shows how the hooks and chain were arranged for lifting a boulder.