One of the theories explaining the reasons for geophagy, which was proposed earlier by the authors of the article, consists in the assumption that animals need rare-earth elements (REE). In order to test this hypothesis, we studied the chemical composition of spring waters in the territory of the Caucasus Nature Reserve at three kudurs along the Achipsta River, as well as at the Mamaevsky kudur (southwestern slope of the Pshekish mountain). At the Mamaevsky kudur, we also studied the chemical composition of earth consumed by animals, and the species, age and gender composition, seasonal and daily activity of ungulate animals–visitors of the kudur. It was determined that the most active visitors of the Mamaevsky kudur were European bison (Bison bonasus) with one activity peak during the rut, in July. The frequency of visits to the kudur by red deer (Cervus elaphus) was 4 times lower with the highest peak activity in April and a lower peak in August. Only in one of four water sources at the Mamaevsky kudur there was an elevated concentration of Na (by 7 times). In the other three the concentration was comparable to the local river water. The waters of two “sodium-free” springs had increased concentrations of REE (by 5–8 times). Geophagic earths near the Mamaevsky springs are decomposition products of siltstone and sandstone shale rocks of the Jurassic age consisting of clay minerals (illite mixed with smectite, and chlorites)—from 42 to 45%, and quartz and feldspar (in total up to 50%) mixed with Fe and Ca carbonates. The chemical composition of acid extracts (0.1 N HCl, pH = 1.0) from consumed earth showed the highest extractability of Ca and Fe. In trace elements, Sr, Ba, Zn, Cu, Ni, Co, V, light lanthanides, and Y are most actively extracted. Na is extracted at 0.03–0.1 g/kg. The sodium bicarbonate spring water consumed by animals at kudurs on the Achipsta River had Na contents 70–300 times, and REE contents 25–40 times higher than that in the river water. The revealed facts do not contradict the hypothesis that the desire for geophagy in animals in the Caucasus (in addition to the long-known “urge” for Na) can be also related to the properties of lanthanides group elements exchange in the body.

本文作者较早提出的解释地理吞噬原因的理论之一是假设动物需要稀土元素（REE）。为了检验这一假设，我们研究了高加索自然保护区沿阿奇普斯塔河沿岸的三个库杜河以及Mamaevsky kudur（Pshekish山的西南坡）的泉水的化学成分。在Mamaevsky kudur，我们还研究了动物消耗的地球化学成分，以及有齿动物的种类，年龄和性别组成，有蹄动物的季节性和日常活动–参观了kudur。经确定，Mamaevsky kudur的最活跃访客是欧洲野牛（Bison bonasus）在7月车辙期间达到一个活动高峰。马鹿（鹿）造访库杜尔的频率。）下降了4倍，4月的最高峰活动和8月的较低峰。在Mamaevsky kudur的四个水源之一中，Na的浓度升高了7倍。在其他三个区域中，该浓度与当地河水相当。两个“无钠”温泉的水域中的稀土元素浓度增加了（5-8倍）。Mamaevsky泉附近的地相地球是侏罗纪时代的粉砂岩和砂岩页岩的分解产物，由42％至45％的粘土矿物（伊利石与绿土和绿泥石混合）以及石英和长石（总计达50％）组成）与铁和钙的碳酸盐混合。从消耗的土壤中提取酸的化学成分（0.1 N HCl，pH = 1.0）显示出最高的Ca和Fe提取率。在微量元素Sr，Ba，Zn，Cu，Ni，Co，V，轻质镧系元素和Y最为活跃。Na的提取量为0.03-0.1 g / kg。动物在阿奇普斯塔河上消耗的碳酸氢钠泉水比河水中的钠含量高70–300倍，而稀土元素含量高25–40倍。所揭示的事实与高加索地区动物对地相吞噬的渴望（除了长期以来对钠的“冲动”之外）还可能与镧系元素在体内交换的特性有关。