Note 160 — Chapter XIX
Reading edition
Messrs. Myers and Forbes found this red clay on the Negro, most abundantly near Barcellos; also in small quantities on the Orinoco above Maipures. The officers of the "Morona" assured us that the same formation was traceable far up the Ucayali and Huallaga. This clay from the Amazon, as examined microscopically by Prof. H. James Clark, contains fragments of gasteropod shells and bivalve casts. The red earth of the Pampas, according to Ehrenberg, contains eight fresh-water to one salt-water animalcule.