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The Secrets Of Green Island

Just one mile west of South Bass Island sits Green Island. Many islanders have looked towards Green and wondered what secrets it holds. They might be surprised to learn there is history both above ground and underground on Green Island.

Neither curiosity seekers nor casual tourists will get onto Green Island anytime soon. The Federal Government owns it. Visitation is prohibited without a special permit. The island is under the jurisdiction of the U.S. Fish and Wildlife Service and is managed by the Ohio Department of Natural Resources as a wildlife refuge. It is dominated by nesting blue herons, double-crested Cormorants, snakes, and lots of poison ivy. It is, however, one of the things to do at Put-in-Bay by boat!

The Island’s modern history traces to 1807 when Alfred P. Edwards bought Green Island, along with South Bass, Middle Bass, Sugar, Gibraltar, Ballast, and Starve. For years, the government wanted to buy at least some of Green Island from Edwards to put up a lighthouse to protect shipping on Lake Erie. Failing that, the Feds wanted a piece of Rattlesnake Island, which Edwards also owned, for the same purpose. Edwards did not wish to to parcel off either island. Eventually, he relented and sold all of Green Island to the Federal Government in 1851.

The Green Island Light Houses

The most noticeable feature of the island is its series of lighthouses. The first one was completed in 1855. A string of lighthouse keepers and their families lived on Green Island over the years, surrounded by a barn and some outbuildings. The original lighthouse burned famously on New Year’s Eve of 1863. A new one was built the following year.

This new beacon remained in service until 1939 when the Coast Guard erected an automatic light on a steel tower. The 1864 lighthouse structure was burned by vandals in the 1950s, and now only its stone skeleton remains, along with the ruins of the other buildings, hidden among the trees and overgrowth.

Since then, the island has been left to grow wild, save for an occasional visit by government employees or researchers. The intriguing part of this history was that, unlike nearby South Bass Island Lighthouse, Green Island has been off-limits and virtually uninhabited since the last lighthouse keeper left in 1939, suggesting the potential for undiscovered cave features.

Green Island Cave Survey

In 2007, members of a caving club called the Cleveland Grotto of the National Speleological Society visited Green Island with special permission from the Ohio Department of Natural Resources as part of the Ohio Cave Survey project. The present authors were part of that team. Due to the lack of any dockage on Green Island, a rowboat had to be towed to the island for landing. For most cavers, a water approach is an unusual thing,
but in Ohio, we tend to take what we can get!

The two most apparent karst (cave) formations we found on the Island were Coil’s Cave, a dome-shaped cave typical of those seen on Put-in-Bay or Kelleys; and the Blue Cenote, an open, roundish 36-foot by 26-foot pit on the Island’s Northside that sits in a crystal-encrusted slump. The Celestine’s veins are typical of the intrusions found in some other caves of the Lake Erie islands, most notably Crystal Cave on South Bass Island. Despite Green’s long history, Coil’s Cave has only been known for a relatively short time.

It was first reported in a 1953 article in the Ohio Journal of Science. The cave was discovered by Mr. Wm. Coil in 1951. Coil observed one bat. Coil’s Cave is a major karst feature and the largest known cave on Green Island. The article reported it was “75 feet x 100 feet in diameter, including a dome about 10- 11 feet high” in the article. An instrument survey of Coils determined that the approximate maximum diameter of the dome cave is closer to 60 feet. So the earlier reported dimensions were somewhat exaggerated but not overly so.

A more typical ceiling height would be five feet with a maximum of eight feet. The longest single-shot survey dimension the survey found was 53 feet, and the maximum diameter in the cave is about 60 feet. The cave reaches about 17 feet below the surface. In a 1953 report, Verber and Stansbery reported that Coil’s Cave appeared to have a “freshly fractured” roof and that it lacked stalactites. That is still true today. The cave itself seems much like the “collapsed dome” type found on South Bass Island: circular, with a high center that narrows towards the walls.

Verber and Stansbery’s report did confirm that Coil’s Cave is “definitely of the Put-in-Bay type.” The cave has little signs of water flow, travertine, and the floor is fairly flat. The roof slopes the same as the other caves, and it is the typical crescent shape of other caves. Coil’s Cave does not have water and appears to be very close to the top of the Tymochtee shaly dolomite, which underlies the Put-in-Bay dolomite. In other words, as opposed to the other islands in the area, the Green and South Bass Islands share the same geological strata.

A Green Island Cave And The A-Bomb

A nearby feature called the Blue Cenote is surprisingly shallow, only about four or five feet deep at its deepest point. Divers have claimed to be able to swim into the Cenote, which sits about 38 feet from the shore of Lake Erie. Given its proximity to Lake Erie, it is no surprise that the Cenote’s water level reflects that of the Lake. The Blue Cenote, perhaps, was a typical Island dome cave that collapsed entirely into the Lake due to its shoreline proximity.

What did come as a surprise to the cave surveyors is the fact that the Cenote is a manmade (or at least man-enhanced) feature which was mined briefly and under great secrecy between 1942-1944. The mining effort was part of the Manhattan Project to develop an atomic bomb during World War II. Green Island was in fact originally known as Strontian Island; however, all of the strontium there was mined out rather quickly.

Exactly when the name changed to Green Island is uncertain, but it was probably between 1840 and 1860. Sources suggest that During World War II, locals with mining experience were hired and sent to Green Island under guard to mine the germanium salts in the strontium sulfate there. Besides its link to nuclear power, germanium was used in early transistor development.

Green Island’s small deposit was one of the few known outside of German-held Africa. The mine’s proximity to Lake Erie proved to be its undoing. Lake Erie water (and fish) apparently got into the Cenote faster than pumps could remove it. As a result, the mining operation was shut down. The whole affair lasted about five days. All of the other known caves on Green Island are small, and their history would appear to date to the Spring 2007 Survey done by the Cleveland cavers when a total of five caves were surveyed.

Among the more obvious of the caves is Easy Find Cave, a horizontal fissure on the shore cliff facing South Bass Island, and Dirty Cave, a muddy pit with loose dirt surrounding the entrance and water at its bottom that likely ties to Lake Erie. The names given to Wedge Cave, Slot Cave, and Grandchildren’s Slot Cave all show that they are small, narrow fissures in the rock of interest more to the critters on Green Island than to any human

Notes: This article is adapted from an earlier survey report of the Cleveland Grotto, which appeared in the NSS News – the official publication of the National Speleological Society. Before this article, the NSS had not published an article about caves in Ohio since the 1950s! This reprise is part of an upcoming NSS publication about Caves of the Lake Erie Islands, anticipated in 2021.

The co-author of this article, Chad Waffen, also has a book about all the islands “Ohio’s Lake Erie Islands” for further reading. Paste “Ohio’s Lake Erie Islands Waffen” into Google for information on obtaining a copy.

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