Born 1812 in London; died Feb. 4, 1880, in Melbourne. French traveler.
Castelnau headed French government scientific expeditions for the study of the Brazilian Highlands and the Amazon Basin. He crossed South America twice. From 1843 to 1845, starting from Rio de Janeiro, Castelnau followed the entire valley of the Araguaia River in the Brazilian Highlands. He ascended the river from its mouth to the valley of the Tocantins River (a tributary of the Araguaia). He continued to the Tocantins’ upper course. Turning westward, Castelnau explored the Mato Grosso plateau, where he established the exact source of the Paraguay River. He then crossed the Chaco Boreal and the Altipiano. After crossing the Andes, he reached the city of Lima. The entire journey, on horse and on foot, covered over 10, 000 km. In 1846 and 1847, Castelnau traveled eastward from Lima, crossed the Andes, and descended the valleys of the Urubamba and Ucayali rivers to 8° S lat. He then descended the Ucayali and Amazon rivers to the sea. This expedition covered approximately 8, 000 km.