Historic Diaries: James Doty, 1820
June 8, 1820: Schoolcraft, on the nearby St. Martin's Islands
Editor's Note:
This is a good example of how the raw material of history, even people's private journals, is not always especially interesting. Unless, of course, one happens to be interested in gypsum.
Gypsum is a chalk-like mineral used today primarily to manufacture drywall. In 1820, it was used to make plaster, an essential material to seal frontier buildings against the hostile winter weather, and as a fertilizer for wheat. Large quantities were imported from Canada at the time, and the discovery of a source for the mineral in the U.S. would have an economic benefit for the young nation.
Location: Big St. Martin Island, Mich.
View original page in Schoolcraft's 1821 Narrative
[Doty did not write in the official expedition journal during his six-day stay at Mackinac, so we substitute the account of Henry Schoolcraft, the expedition's geologist:]
In consequence of a reported discovery of gypsum upon the St. Martin's islands, which belong to the Michilimackinac cluster, I was directed by Gov. Cass to make a mineralogical survey of those islands, and to report upon the quantity and the quality of the gypsum found… We were favoured with a wind, and after accomplishing the object of the voyage, returned to the harbour of Michilimackinac before dark. The St. Martin's islands lie about ten miles northeast of Michilimackinac. The largest is about nine miles in circumference, by three broad at the widest part, and consists of alluvial soil, covered partly with a forest of oak, maple, and poplar. In no place does it attain an elevation of more than twenty feet above the level of the lake, and it is subject to a partial inundation in the spring, when the sudden melting of the northern shows produces a rise of water in the lake.
Imbedded in this soil, which appears naturally fertile, we found large detached masses of gypsum, of a very fine quality, and unconnected with any adhering rock, so that no expense of blasting is necessary… Altogether the specimens bear a greater resemblance to the Nova Scotia gypsum, of which such quantities are annually imported into the United States, than any of the numerous beds hitherto discovered in New-York, and other sections of the Union. And, if an opinion may be drawn from external characters, we may venture to consider the St. Martin's, or, as it is already called, the Mackinac gypsum, of a superior quality for agricultural purposes. As to the quantity in which it exists, nothing can be decisively stated, as the earth has not been much explored; but from the abundance which is scattered over the surface of the ground, and from other geological appearances, it is probable that the quantity will prove exhaustless.
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