Surface and core samples of Neh–nar Glacier in the Kashmir Valley have been analysed for the radionuclides 32Si. 210Pb, 40K, and 137Cs. The lateral and vertical profiles (at an altitude of about 4 140 m) reveal:(1)32Si activity decreasing slowly from the accumulation zone to 4 050 m altitude and then abruptly towards the snout.(2)Five zones of alternating high and low 210Pb activity in the surface samples.(3)An horizon at between 2 and 3 m depth containing 210Pb activity above natural levels. This horizon is also associated with 137Cs and a maximum in total ß activity.The ice samples have been dated on the basis of a simplified two–component model, the “fresh“contribution determined by 2l0Pb and the old component by 32Si. The following conclusions can be drawn from these observations:(1)The model age of the snout ice is c. 850 years.(2)The average rate of ice movement in the lower glacier is about 2 m/year, which compares well with the annual movement rate of 2.65 m/year observed since 1974.

ABST RACT. The 32Si concentra tion in a sample of surface ice from the sn o ut or Cha ngme-Khang pu glacier is 0 .36 disintegra tions pe r minute/tonne compa red to the ra il-o ut value of 0 .7 d .p .m ./tonne. If this d ecr ease is assumed to be solel y due to d ecay of 32Si , a n age of c. lOO years is estimated for the surface ice of the snout, leading to an avera~e fl ow velocity of c. 40 m/year for th e pas t centu ry. A vertical profile of ' °Pb in a core ta ken a t a n a lti tud e of 5040 m shows two h ori zons where this isotope is enriched , one between 3 a nd 4 m and a no ther between II a nd 12 m , indicating th a t the prima ry con centra tion of "o Pb can cha nge by phys icoche mical processes like a d sorption on dust. Non e the less, a longitudina l p rofil e a long the glacier shows a sys tema tic decrease of 'l oPb acti vity w ith d ecreasing altitud e, the surface ice of the snout giving a value orO.2 d .p.m ./I, corres ponding to a n age of 100 yea rs which is con cordant with the 32 Si age. This surface flow-ra te of the glacier is much la rger than the average contempora ry fl ow-ra te (c. 13 m /year ). The di ffe rence ca n b e understood in terms of the pas t history of a dvance a nd recession of the g lacie r as revealed by the geom orp hi c evidence. 'au tre ve rs 11-12 m , indiqua nt que la concentra tion ori gi nelle du " oPb peu t etre modifiee pa r d es processus ph ys ico-chimiqu es tels que I' adsorption sur les po ussieres. Enfin un profil lo ng itudina l mo ntre une I NTR ODU CTI ON Changme-Khangpu glacier is located in the Tista river baSin, in the upper catchment of one of its major tributaries, Lachung Chu, in the Sebu valley of north-east Sikkim. It is a transverse valley glacier trending north-south, having a length of 5.87 km and width varying between 600 m to 1 km. The glacier originates from the southern slope of Gurudongmar peak (lat. 27°58'N., long. 88°42'E.) which is an integral part of the Khangchengyao-Pauhnri massif. The melt water of the glacier feeds into the Sebu Chu, a tributary of Lachung Chu.The area1 coverage of the glacierized part of the Changme-Khacngpu basin is about 12.85 k~, of which 10.35 k~ comes under perennial ice cover and the rest is covered by rock surfaces only. The ratio between the accumulation and ablation zone areas is 5:7. Almost the entire ablation zone of the glacier is under a thick mantle of suprag1acia1 morainic debris (Bhattacharya, unpublished). The terminal part of the glacier is completely buried under the moraine which has generated enormous amounts of dust which is present everywhere. Presence of eng1acia1 dust is also well documented in the darker ice bands exposed in the vertical to subvertical faces. The lowest part of the snout is located at an altitude of 4850 m a.s.1. This part, when exposed from the suprag1acia1 debris, is about 3 m in height and 7 m in width. Radiomelrische Chron%gie des Changme-KhangpuCle15chers, Sikkim. Oie 32Si-Ko n zentra ti on in einer Probe des O berfl iicheneises a us d er Zunge d es C h a n gme-Kh...

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