Abstract:

Rock-block field is a special geomorphic type mainly developed in bedrock slope zones, formed under diverse geodynamics and complex geologic processes, and its formation has been controversial for a long time.The spectacular rock-block field in Beidashan, Chengde County, Hebei not only is the main landscape and tourism resources of the forest park, but also provides unique conditions for studying the origin of the rock-block field.We conducted a systematic investigation on the rock-block field geomorphology in the Beidashan Forest Park, mainly using the field geological survey, gravel statistics, and UAV aerial modeling methods.The study results show that the gravel source of rock-block field came from the collapsed granite which is fractured and broken due to the joints at the top of gully; the huge gravel composed of the rock-block field has the characteristics of gravity collapse and short distance water transportation, which is not consistent with the characteristics of glacier or debris flow transport.The freezing and thawing separation is the main driving force causing the huge stones to emerge from the surface and then forming the rock-block field.In this study, we proposed a new interpretation on the origin of freeze-thaw sorting of the rock-block field landform in Beidashan, Chengde for the first time.This study not only promotes the theoretical studies of rock-block field origin, but also provides an important reference for the formation of rock-block field landform in other places.

Key words: rock-block field, gravity collapse, freeze-thaw action, tourism earth-science, Beidashan Forest Park, Chengde