Settlement Quarry EarthCache
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Deer Isle’s “pink feldspar” granite rocks! This earthcache gives you a peak at Maine’s geologic and social history as shown through the patterns and color of granite, one of the unique wonders of Maine’s timeless mystique.
Welcome to Settlement Quarry where the obsolete equipment still stands rusting and disused as a testament to the importance of this location to the island community at one time. The geologic story of this location begins long ago as the Iapetos Ocean was shrinking as continent of Avalonia was separating. The continental collision forces began about 423 million years ago in late Silurian time, and culminated in mid Devonian time, some 383 million years ago. The igneous activity at that time was occurring off the coast. Granites were intruded into deeper parts of the crust, and volcanoes probably dotted the landscape above these intrusions. The Deer Isle Granite was formed at this time, as were several other granite bodies along the coast. The granite of Cadillac Mountain on Mr. Desert Island was one of these. Geochemical evidence suggests that the Deer Isle Granite was located at a depth of about 8 km (5 miles), so this much rock has been eroded away since the Acadian Orogeny (the Appalachian mountain building period) by the past glaciers. Granite forms as magma, molten rock deep within the earth. When magma solidifies within the earth the resulting rocks are called intrusive or plutonic rocks. The grain size of the granite is determined by how fast or slow the molten rock solidifies. Fast-cooling magma forms small crystals, while slow-cooling magma forms large crystals deep in the earth. The erosion and uplift of the overlying rock exposes these plutonic rocks to the atmosphere. Granite is a light-colored igneous rock made up of fine- and coarse-grained crystals of quartz and feldspar. Often dark crystals of mica or hornblende are mixed in the rock giving it a salt and pepper look. The color of granite, often important in its value as a building stone, is mostly determined by the color of the feldspar.
C. T. Jackson published the first geologic survey of the state of Maine in 1837. He inventoried Maine's economic deposits, including some of Maine's granite quarries, and concluded that Maine would be able to support an active mining industry. By the late 1800's the industry was thriving along mid-coast Maine and on some of the offshore islands. The Settlement Quarry location became ideal due to the shape of this small mountain a result of glaciation as the glaciers ground and polished the slope, making the striations in the rock that can still be seen today. The steep lee slope provided quarry operators with good access to the granite sheets with the best spacing, and access to a good harbor from which to ship the stone to construction sites throughout New England. The other noteworthy feature of the Settlement Quarry is the fracture or joint system. The near-vertical fractures were probably formed during the closing phases of the Acadian Orogeny. However, the nearly horizontal sheet fractures were formed as the overlying rocks were eroded away. When the pressure was reduced by erosion, the granite tried to expand perpendicular to the Earth's surface forming parallel fractures. Quarry operators made use of these fractures when removing blocks of rock. Fracture spacing is an important consideration in opening a quarry, but the vertical spacing of the fractures must be neither too large nor too small.
Settlement Quarry was started in 1900 with two openings on the top of the hill 500 by 400 feet with its initial operation consisted of 9 derricks, 1 traveling crane, 2 compressors, 9 surfacers, 2 steam pumps, 1 locomotive, 16 steam pneumatic drills, 19 pneumatic plug drills and 8 pneumatic hand tools. In 1902, the quarry exported its first load of “pink feldspar” granite. It went to New York City and into the abutments of the Williamsburg Bridge then being built. Perhaps the most famous example of Deer Isle granite, done by stone cutting craftsmen, several of who still live on Deer Isle, was the President John F. Kennedy’s memorial at Arlington National Cemetery.
If you look around carefully you will find a fallen forest of stacks, masts, booms, cables and derricks. There was a coal-fired boilers used to generate the steam to run the engines that operated compressors, dynamos, winches, and cranes. There was even a railroad for moving granite and machinery within the site. Frank McGuire took over the operation as the Deer Isle Granite Corp. in 1923. He moved the sheds at Crotch Island to the Settlement quarry, which you see now as a steel building below near the shore. In this building granite saws were used to cut the blocks. As you look around the quarry you will find evidence of a variety of cutting methods. Granite cut with a silicon carbide wire saw leaves a very smooth cut. Larger blocks were cut with a burner using liquid oxygen and kerosene with water and compressed air leaving a rounded uncut edge. Blocks cut with a very jagged and uneven edge were cut using a water jet cutter. Granite was commonly quarried using steam drills, wedges and hammers. Steam drills drilled holes along the hard edge of the granite, perpendicular to the grain of the rock. Along the grain of the rock (easy direction of splitting) wedges with feathers were used to easily break off the slabs. Derricks were used to move the blocks up out of the quarry onto horse drawn wagons called galamanders.
What made the granite so easy to cut in its early year was blamed for the demise of the quarry, the fracture system. The old quarry is now just an empty industrial reminder of the Island’s industrial past. The pieces of obsolete equipment, not worth the trouble to remove, still stand rusting and disused around the quarry often hidden by the slowly returning forest. It is the beauty of this stark location that offers a unique allure to the explorer. So take some time to get out and stretch your legs while you explore the great coastal granite quarrying history of the past.
The posted coordinates will bring you to the eastern opening of the quarry; here the trail splits allowing exploring in both directions. The right trail takes you along the north edge of the quarry while the other trail takes you down into the outer south section of the quarry. Remember this is an earthcache so there is no container just an earth science lesson at an amazing natural feature. To log this cache, you must post a photo of yourself or your hand with your GPS showing the view of the one of the interesting features of the quarry in the background and then email me through my profile the answers to the following questions: What is the average thickness of the sheets of granite produced by the natural horizontal fractures in the rock? Please make sure to include the name of the earthcache in your email.
This Settlement Quarry Preserve is owned and maintained by the Island Heritage Trust, a non-profit private land trust dedicated to conservation that protects significant open space, scenic areas, wildlife habitats, natural resources, and historic and cultural features that offer public benefit and are essential to the character of the Deer Isle area. You may want to look at their website at: (visit link)
For further information you may want to visit:
Deer Isle Granite Museum, 51 Main Street, Stonington, ME 04681, 367-6331
(July 1 thru August 31)
If you enjoy this earthcache you may want to check the Maine Geological Survey located at (visit link)
They have developed a number of information sheets or field localities giving a great deal of information about geologic features. They also have a number of books and maps about Maine’s natural history/ geology that you might find interesting.
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