Distribution and Features of Glacial Landforms in the Northwest of the Die Shan,West Qinling Mountains

The northwest of the Die shan,as the western segment of the Qinling Mountains,is located in the eastern margin of the Qinghai-Xizang Plateau.Glacial erosional and depositional landforms,including cirques,U-shaped valleys,hanging valleys,palaeo-firn basins,whaleback rocks,polished bedrocks,and lateral and end moraines are well preserved in this mountainous area above 3 700m a.s.l.Remote-sensing techniques and field mapping were applied to study the distribution and features of glacial landforms in this area.Based on the distribution and features of glacial landforms,considering the present uplift speed of the Qinghai-Xizang Plateau,the available dating data of the glacial landforms in the Dalijia Mountain and the data of the palaeoenvironment in the neighboring areas,the glacial landforms are considered to be formed in the last glacial cycle,especially during the Last Glacial Maximum.The ancient glacier was an ice cap with a maximum area of about 38km2.Abundant whaleback rocks that present at about 4 200ma.s.l.indicate that the ancient ice cap had a warm bottom.