Latest Issue

2024 Vol.133 No.2

Landscape of the Upper Reaches of the Orkhon River, Khangai Mtns., Mongolia

Readers might imagine that huge deserts and extensive sheep-filled grasslands are typical landscapes of Mongolia; however, it is a mountainous country. To the north and west there are wild, non-vegetated hills and rugged ridges, with high snow-covered peaks reminiscent of the European Alps. The Khangai mountains in central Mongolia, extending ca. 1000 km in length and ca. 200 km crosswise, form a dominant massif composed mostly of Paleozoic orogenic products, such as accretionary complexes, volcanics/granitoids, blueschists, and ophiolites. The cover photo shows a typical landscape of the mid-Khangai mountains, along the upper reaches of the Orkhon River. The exposed basement rocks are components of the Devonian accretionary complex, e.g., bedded chert: a section of ancient deep-sea floor from the Paleo-Asian Ocean. From a prominent chert ridge, we can clearly observe well-preserved natural landforms, such as a sedimentary fan and braided river system, free from obstacles (vegetation and human artefacts), with nomadic gels (temporary tent-like structures) providing scale. The flat plane on the opposite riverbank is not a river terrace but a flow surface of Quaternary flood basalt. Japanese readers may have read the popular historic novel Pale Wolf by Yasushi Inoue, based on the ancient document The Secret History of the Mongols, which tells the life story of Genghis Khan. The Orkhon River appears often in this novel, reminding us of the frequent long journeys he made across this river with his warriors and family. The natural landscape appears not to have changed much in the millennium since the time of Genghis Khan.

(Photograph & Explanation: Yukio ISOZAKI)