Relevance. For the first time, comprehensive landscape-geochemical studies were conducted in the Buotama, Amga and Vostochnaya Khandyga river basins of Yakutia. The studies included the chemical composition of natural waters, soils, forage grasses, and rocks eaten by animals on kudurs, landscape complexes visited by animals for long periods of time for geophagy and specifically transformed by them. Aim. To determine the cause of geophagy occurring in these areas among wild and domestic animals. Methods. Atomic emission spectrometry, mass spectrometry, ion chromatography, analytical electron scanning microscope with energy-dispersive spectrometer. Results. It was revealed that geophagy in Yakutia is widespread both in mountainous and flat areas in landscapes with low contents of mobile forms of rare earth elements that can accumulate in feed and drinking water. It is assumed that the deficiency of rare earth elements in the diet of animals causes a disruption in their body metabolism of this group of elements in the nervous and endocrine systems, which is accompanied by specific hormonal stress. The state of stress forces animals to look for ways to minimize the problem that has arisen. They solve it by consuming mineral or organomineral sorbents (mainly clay rocks and peat soils) relatively enriched with rare earth elements in places where they are slightly saline, mainly with carbonate salts of calcium, magnesium and sodium. Such salts create an alkaline environment favorable for the formation of clay mineral sorbents that are capable of accumulating ions of rare earth elements. In addition, sodium salts, by affecting the central nervous system, help animals alleviate the state of stress.