On July 3, 1804, Captain Clark passed Cow Island, a large island known to the French as Isle de Vache, opposite a large pond containing beaver and fowl, and he later halted at a deserted old trading house used by French merchants trading with the Kansa Indians, where a very fat horse was found. The land between this site and the present-day river was Cow Island, named because French traders kept cows there in the 1700s, and the island was where the Iatan Power Station is located today. The nearby pond still exists as Iatan Pond, and members of the expedition first saw beaver in this area, an important observation because President Jefferson had asked Lewis and Clark to record where beaver were found and how abundant they were because of their value in the fur trade. Sergeant Ordway also praised the good high bottom land and its timber, including black walnut, honey locust, oak, and what was probably the Ohio buckeye. One purpose of the Corps of Discovery's journey was to gather detailed information about Native Americans, including tribal names, languages, populations, trade, furs, allies, enemies, and the streams and rivers where they lived or traveled. Although Lewis and Clark saw no Indians here, they did see deserted villages, and on September 24, 1806, Clark expected to see members of the Kansa tribe in this part of the Missouri because they resorted there at that season of the year.