Late Quaternary Moraines of the Ngojumba Glacier, Khumbu Himal, Eastern Nepal

Abstract

Late Quaternary glacier variation of the Ngojumba Glacier in the Khumbu Himal are determined by detailed field mapping of glacial landforms, stratigraphy of fossil soil, S-1, S-2, and S-3 in desending order, and ¹⁴C-dates of fossil soil horizon.
The moraines of different ages indicate seven advance stages as follows ; the Gokyo stage, the Nah stage, the Machhermo stage, the Dole stage, the Phortse Drangka stage, the Phortse stage, and the Konar stage. The Gokyo and Nah stages, of which moraines are covered with very thin S-1 soil correspond to the period from the Little Ice Age of A.D. 19-16c. to the middle Neoglacial readvance. Since the moraines of the Machhermo stage are covered with S-2 soil of 600-5, 000 y. B. P. by ¹⁴C-dating, were probably formed during early Neoglaciation, 7-8 ka. The moraines, overlain by S-3 soil, of the Dole and Phortse Drangka stages are much larger than those of other stages in size, and two stages probably correspond to the Last Glacial Stage. The Ngojumba Glacier in the Phortse Drangka stage, the Last Glacial Maximum, extended 8-9km downstream (3, 500m a. s. 1.) from present glacial terminus (4, 700m a. s. 1.). The Phortse and Konar stages are included among the glacier advances before the Last Glacial Stage because their moraines are well-erod and covered with thick soil layers.