Lewis & Clark Corps of Discovery (1803-1806)

In May 2025, I spent two weeks as a cruise ship historian on the Snake and Columbia Rivers. I prepared a series of four hour-long talks on the 1804-06 expedition led by Meriwether Lewis and William Clark. The expedition was commissioned by Thomas Jefferson as an exploratory trip to discover the lands and natural history of the Louisiana Purchase of 1803. This page is developed from those talks. I also prepared a talk on the geology of the region, which includes both volcanic activity and the famous Ice Age "Bretz Floods". The Corps of Discovery talks gave me a strong understanding of the natural history of the American continent over the same time period as Brongniart and Cuvier's eartliest investigations of the Paris Basin, which officially began in 1802.

Meriwether Lewis in Washington

Preparations and Planning

Before the trip could begin, Meriwether Lewis had to gain specialized skills including navigation, surveying, mineralogy, geology, natural history, and field specimen preparation. He left his role as secretary to Thomas Jefferson and eagerly went about learning all of the skills he would need (including medical study) in order to take on the leadership of this challenging expedition. Interestingly, Brongniart's youngest sister, Émilie, as the wife of the diplomat Louis-André Pinchon, was a close associate to both Jefferson and Lewis at this time. As this page develops, I will show the deep connections between Lewis and Clark, Thomas Jefferson, and the Brongniart family in Paris and in the US.