Abstract
The authors interested in the selective occurrence of the earth hummocks along the former river channels of the flood plain near the junction of the Harh river (_??__??__??__??__??__??_-_??__??__??_) and the Onon river (_??__??__??__??_-_??__??__??_), northeast Mongolia.
Some hand-bore tests and the small trench excavations had revealed the coincidence between the occurrence of frost involution and the belted existence of the clayey fine sand layer along the former river course, which might controlled the beginning of the earth hummmock formation. The earth hummocks are not found on the natural levee surface of gravels. The micro-relief formed by frost action may not be a fossil one but a current. The center of former Bindel-Som (village) had moved from the flood plain to the present site on the hill-foot gravelly surface some decades ago, as we heard, to avoid the frost heaving.
