Lake Superior reaches a depth of 1,335 feet, and that pothole you hit last spring sure felt like it was 2,000 feet deep, but those pale in comparison to a hole drilled in the '70s.

Oil exploration in the State of Michigan reached a fever pitch in the '70s due to the Arab oil embargo. So great was the demand that geologists drilled a hole in hopes of finding natural gas or oil just south of Ithaca, in the central part of the Lower Peninsula.

The initial permit issued by the state allowed the McClure Oil Company to drill to 11,000 feet in search of black gold, Texas tea. (sorry, I couldn't help it)

After getting to 9,695 feet, the drill bit broke, and the drillers had to fish it out. But they kept going.

In April of 1975 they hit 13,000 feet, which was the state record for the deepest drill, but they kept going.

According to Central Michigan University's History of Oil and Gas Exploration web site, the drilling started getting weird, and strangely colorful:

At 12,193 feet the drill bit began to chew into an unfamiliar red formation described as predominantly shale with sand flecks. This red stuff was to last for over 5,000 feet, baffling all comers.

In October, 1975, a fourth drilling coring operation was run from 17,409 feet to what was later declared final total depth at 17,466 feet. The red stuff had come to an end when some green material was encountered at about 17,000 feet. Time, materials and resources exhausted, the decision was made to stop drilling. The hole was declared dry. However, before it was plugged and abandoned, the National Science Foundation and other earth scientists swarmed the location.

By the way -- the deepest hole ever drilled was in Russia on the Kola peninsula, where in 1970 Soviet researchers reached over 40,000 feet.

The deepest sinkhole in Michigan is the Bruski sinkhole in Posen, west of Alpena at over 100 feet deep.

And the deepest pothole? About 13 inches.

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