Charles Frederick Hartt (23 August 1840 in Fredericton, New Brunswick – 18 March 1878) was a Canadian-American geologist, paleontologist and naturalist who specialized in the geology of Brazil.

In 1860, he accompanied his father, Jarvis William Hartt, to Saint John, New Brunswick, where they established a high school for young women in which Charles Frederick taught for a year.

But in the 21st century, additional research was funded to answer hypothetical concerns about the potential extinction of the entire Amazonian ecosystem during predicted global warming.

[1] In 1868 he was elected professor of natural history at Vassar College, but later in the same year he accepted a post at Cornell University, in Ithaca, New York, and planned to return to Brazil.

In his last voyage he collected more than 500,000 specimens, which were donated to the National Museum of Rio de Janeiro, where he worked as the founder and director of the section of geology from 1866 to 1867.

Agassiz died earlier, in 1873, before major discoveries could provide substantial fossil evidence and before the neo-Darwinists improved Darwinism by asserting the Weismann barrier in 1893.

Hartt had gathered useful specimens in Brazil that could be explained by the 20th century Darwinian narrative of accelerated evolution, which hypothesized that Amazonian butterflies survived in isolated refuges during ice ages.

[12] One of Hartt's students, the American geologist Orville Adalbert Derby (1851–1915), succeeded him at the National Museum, after having accompanied him in two of the Morgan Expeditions (1870 and 1871) and having worked with him at the Imperial Commission.