John Leonard Riddell: From Rensselaer to New Orleans (1827-1865)

John L. Riddell, though primarily interested in chemistry, botany, and medicine, made considerable contributions to geology. From 1827-1829 he was a student at Rensselaer under Amos Eaton, the first American teacher of geology. Riddell's first scientific lecture, A new theory of the earth, was delivered at Rensselaer in August 1829. It dealt with geological formations and the fossil remains contained therein.

From 1830-1832 Riddell presented public subscription lectures in New York, Ontario, Pennsylvania, and Ohio. Late in 1832 he became professor of chemistry and botany at the Ohio Reformed Medical College, where he began to study the geology of the state. Geology of Ohio, his first formal paper on geological subjects, appeared in 1833. Others papers soon followed. He worked with Samuel P. Hildreth on Survey of the geology of Ohio, which was completed in 1836. Soon afterwards, Riddell married and moved to New Orleans, becoming professor of chemistry at the New Orleans Medical College, now Tulane University. He remained in New Orleans until his death nearly thirty years later.

In 1839 Riddell attempted to secure state authorization to conduct a geological survey of Louisiana. Also in 1839, he made two excursions to Texas, resulting in his Geology of the Trinity Country, Texas, published in 1839. Finally, in 1841, the Geological Committee of the State of Louisiana was formed, with Riddell as Chairman. There were five other members. Tragically, the result of their work was lost before being published, and no trace of the manuscript is known to exist today. In his later years, Riddell continued to do geological work, including studies of Mississippi River dynamics. He also continued his long teaching career in New Orleans.