FROM CONCORD TO THE LOWER SIOUX AGENCY AND BACK: GEOGRAPHIC AND GEOLOGIC OBSERVATIONS OF HENRY DAVID THOREAU AND HORACE MANN, JR., ON THEIR EXCURSION TO MINNESOTA, MAY–JULY 1861
In Minnesota they visited St. Anthony Falls, Minnehaha Falls, Lakes Harriet and Calhoun, Carver’s Cave, and Fort Snelling. Starting on 17 June, they traveled on the steamer “Frank Steele” up the Minnesota River to the Lower Sioux Agency to observe the granting of annuities to the Sioux and related festivities. Upon returning to St. Paul on 22 July, they decided to cut their sojourn short. Taking a boat south, they stopped at Red Wing, MN, to explore and botanize on Barn Bluff for 4 days. On 26 July they began the long trip back by boat and train, stopping for 5 days at Mackinac Island, MI. They arrived in Concord on 9 July.
Although both Thoreau and Mann’s consuming interest in their travels was botany, they made numerous observations on the landscape and geology. They commented on the “dune hills” and building stones of Chicago; the bluffs along the Mississippi; the digging of “poor” stone (Platteville Limestone) for buildings out of their cellars in St. Paul; the many swallow holes in the “very soft and crumbly” St. Peter Sandstone; the quarries in the red Sioux Quartzite near New Ulm; and the physiography of Barn Bluff, with its still-evident “double path.” Thoreau well described the wild meanders of the underfit Minnesota River—noting that it was 250-300 river miles from St. Paul to the Lower Sioux Agency, a crowflight distance of ~120 miles.
Thoreau’s attempt to improve his health was unsuccessful. His condition continued to worsen, and by December 1861 he was confined to the “Yellow House” in Concord, where he finished writing several of his classic essays, including “Walking,” and died on 6 May 1862. Horace Mann, Jr., went on to become a noted Harvard-educated, but short-lived, botanist. He died in 1868 of tuberculosis, possibly contracted from Thoreau on their Minnesota excursion.