By stratigraphic means

the paper makes division and comparison tothe geological sections from sedimentary bodies of debris flow in thelate pleistocene in Wudu

establishing synthetic geological columna sec-tions of the debris flow of this period

it also analyses the characteristicsof sedimentary facies in detail. The sedimentary bodies of debris flow inthe period are composed of mud flow facies

sheet flow facies

whichbear relationship on the action of debris flow

and alluvial facies andloess soil facies which have nothing to do with the action of the debrisflow.From this the paper deduces the forming environment of them

ex-plores the relationship among the occurence

ceasing

new tectonism andclimate of the debris flow

and then the action period of debris flow isdivided into four action phases.