GEOLOGICAL TRAILBLAZERS: OBSERVATIONS OF WESTERN GEOLOGY IN THE JOURNALS OF LEWIS AND CLARK

The journals of Captains Meriwether Lewis and William Clark, written between 1803-1806, contain hundreds of informative geological, geomorphologic, sedimentological, and economic geology observations obtained during their epic expedition across the continent of North America. The Captains methodically noted a wide array of rock lithologies, diligently recorded the appearance of coal and other mineral resources such as salts, clays, and limestone, made inspired inferences on river depositional processes, and speculated intelligently on erosional phenomena, in addition to documenting soil fertility, bottomlands vulnerable to flooding, and rocky watercourses that resisted unimpeded navigation. On the outbound journey from Camp Dubois near St. Louis to Fort Clatsop on the Pacific Coast, encompassing some 320 travel days, the Captains made some type of geological notation (e.g., notes on stratigraphic relationships, types of mineral resources, observations on erosion or mass wasting, etc.) in greater than 45% of their daily journal entries over this time period. If the myriad of sedimentological observations (e.g., notes on “ancient beds of the river”, the type of sediments carried by the various waterways, the cut and fill depositional hydraulics of river channels, etc.) are included in this calculation, the percentage of the Captains’ daily geological notations exceeded 60%. This is a remarkably complete and relatively continuous account of the geological terrain of the expedition route and one that is simple to recognize and retrace 200 years later. Additionally, the perceived ‘gaps’ in geological observations in the journals were not due to a lost of interest by the Captains, as some historians have asserted, but was a result of the nascent state of the geological sciences in 1803 (particularly the lack of proven theories of geological processes) and the relative ease in rock and mineral identification that could be accomplished in an expeditious manner. Thus, the Lewis and Clark Expedition should rightly be considered the true forerunner of the late 19th century federal geological/topographical surveys of the American West.