His geological report to the same department made subsequently, traces the formations of that part of the continent, which gives origin to the Mississippi River, and denotes the latitudes where it is crossed by the primitive and volcanic rocks.

The ardor and enthusiasm which he evinced in the cause of science, and his personal enterprise in traversing vast regions, awakened a corresponding spirit; and the publication of his narratives had the effect to popularize the subject of mineralogy and geology throughout the country.
In 1821, he executed a very extensive journey through the Miami of the Lakes and the River Wabash, tracing those streams minutely to the entrance of the latter into the Ohio River.

He then proceeded to explore the Oshawanoe Mountains, near Cave-in-Rock, with their deposits of the fluate of lime, galena, and other mineral treasures.

From this range he crossed over the grand prairies of the Illinois to St.Louis, revisited the mineral district of Potosi, and ascended the Illinois River and its north-west fork, the _Des Plaines_, to Chicago, where a large body of Indians were congregated to confer on the cession of their lands.

At these important conferences, he occupied the position of secretary.