GEOLOGY: THE FORGOTTEN SCIENCE OF THE LEWIS AND CLARK EXPEDITION

In his letter to Meriwether Lewis that outlined the expedition, President Thomas Jefferson directed the explorer to note not only the native people, plants, animals, but also "mineral productions of every kind, but more importantly metals, limestone, pit coal & saltpeter; salines & mineral waters noting temperatures of the last & such circumstances as may indicate their character, volcanic appearances...." Clearly, Jefferson recognized the importance of geologic features, but through the last two hundred years the geologic items observed and noted by Lewis and Clark and the role of these items and place in the outcome of the expedition have been overlooked. The geographic features observed and the obstacles encountered and surmounted by the expedition were geological in nature. The trail of preparation took Lewis to Harpers Ferry, West Virginia, through the Appalachian Basin, down the Ohio River, over the Falls of the Ohio, and eventually to St. Louis. Their 1804 sojourn saw the Corps of Discovery pass glacial features such as the Council Bluffs and the Great Bend of the Missouri. In 1805 the expedition portaged the Great Falls, passed through the Gates of the Rocky Mountains, and then scaled the Beaverhead and Bitterroot Mountains on their way down the Columbia River. The 1806 return trip took Lewis past the Lewis Overthrust and Clark down the Yellowstone River through Cretaceous outliers at Pompey's Column. Ultimately, their route down the Ohio and up the Missouri Rivers was controlled more by Pleistocene glaciation than it was by Presidential orders.