Zenas Leonard (1809-1857). Clearfield native and fur trader, Leonard was second in command of the Joseph Reddeford Walker Expedition from 1831-1834 to find a route to the Pacific Ocean through the Sierra Nevada Mountains. Leonard served as the expedition''s clerk and chronicler, recording the first non-native American encounter of giant sequoia trees. In 1839 Leonard published his account of the expedition, recognized for its detailed descriptions.