Abstract:The origin of giant arc sand ridges widely distributed in Horqin sandy land of Songliao Plain has not been clearly explained. Through analyzing geomorphological characteristics, such as giant arc longitudinal dune, intensive lake bubbles and so on, by using deformation mechanism of Rogan moraine, it is found that the characteristics of longitudinal dune is identical with under-ice softlandforms in Scandinavian and Lauren tade ice sheet. It is confirmed that giant streamline, Rogan moraine, pothole are formed by ice sheet. It has revealed the existence of Songliao ice sheet. It is found that the giant arc streamline in Songliao plain shows the characteristics of extending and converging from the surrounding of the basin to the subsidence center. It is showed that the direction of the streamline is controlled by topography rather than wind. In addition, according to the abnormal relation between the spread form of the giant glacier streamline and the Songliao ice sheet, it is found that the latter moved northward after melting, which may be related to rebound upliftreliefingpressure caused by melting. According to comprehensive analysis of migration time and sequence age and load structure disturbance stratum age in Songliao ice sheet, it can preliminary determined that the last occurrence time of Songliao ice sheet is in Dongshan Ice Age in the early period of late Pleistocene (MIS4 stage).
