Rock of Ages Light
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Undated USCG photo
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| Location | Isle Royale, Michigan |
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| Coordinates | 47°52′00″N 89°18′48″W / 47.86667°N 89.31333°WCoordinates: 47°52′00″N 89°18′48″W / 47.86667°N 89.31333°W |
| Year first constructed | 1908 |
| Year first lit | 1910 |
| Automated | 1978 |
| Foundation |
Concrete Pier Steel Caisson |
| Construction | Steel, Masonry, Concrete |
| Tower shape | Cylindrical base/Frustum of a Cone tower |
| Markings / pattern | White Black base and lantern |
| Height | 117 feet (36 m) |
| Focal height | Focal plane - 130 feet (40 m) |
| Original lens | 2nd Order bivalve Fresnel Lens |
| Current lens | 12-inch (300 mm) Tideland Signal ML-300 Acrylic Optic |
| Range | 15 nautical miles; 27 kilometres (17 mi) |
| Characteristic | two flashes every 10 s |
| ARLHS number | USA-698 |
| USCG number |
7-16655 |
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Rock of Ages Light Station
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| Nearest city | Grand Portage, Minnesota |
| Area | 0.1 acres (0.040 ha) |
| Architect | Keller; Beger, Walter F. |
| MPS | U.S. Coast Guard Lighthouses and Light Stations on the Great Lakes TR |
| NRHP Reference # | 83000881 |
| Added to NRHP | August 04, 1983 |
7-16655
The Rock of Ages Light is a U.S. Coast Guard lighthouse on a small rock outcropping (50 by 200 feet (15 m × 61 m)) approximately 2.25 miles (3.62 km) miles west of Washington Island and 3.5 miles (5.6 km) west of Isle Royale, in Eagle Harbor Township, Keweenaw County, Michigan (see map below). It is an active aid to navigation.
The period between 1852 and the beginning of the 20th century saw great activity on the Great Lakes by the United States Lighthouse Board. Between 1852 and 1860 26 new lights were built. Even as the United States Civil War and its aftermath slowed construction, a dozen new lights were still lit in that decade. In the 1870s, 43 new lights were built on the Lakes. The 1880s saw more than one hundred lights constructed.
As the new century began, on the Great Lakes the Lighthouse Board operated 334 major lights, 67 fog horns and 563 buoys.
During the 19th century design of Great Lakes lights slowly evolved. Until 1870 the most common design was to build a keeper's dwelling with the light on the dwelling's roof or on a relatively small square tower attached to the house. In the 1870s, so as to raise lights to a higher focal plane, conical brick towers, usually between eighty to one hundred feet tall were constructed. In the 1890s steel lined towers began to replace the older generation of brick building.See Big Sable Point Light for a striking transition and transformation.
The Rock of Ages Light was part of a forty year effort—between 1870 and 1910—where engineers began to build lights on isolated islands, reefs, and shoals that were significant navigational hazards. To that time, Light ships were the only practical way to mark the hazards, but were dangerous for the sailors who manned them, and difficult to maintain. "Worse, regardless of the type of anchors used lightships could be blown off their expected location in severe storms, making them a potential liability in the worst weather when captains would depend on the charted location of these lights to measure their own ship's distance from dangerous rocks."See, United States lightship Huron (LV-103).
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Wikipedia