关于金字塔沙丘成因的探讨

DISCUSION ON THE CAUSEOF FORMATION PYRAMIDAL DUNES

在考察中首次发现金字塔型沙丘，初步探讨了形成这种沙丘的环境因素。

Pyramidal dune,geomorphy of wind deposites Abstract Pyrsamidal dunes have some characteristics such as high and vast sand body,special form,steady and rarely moving,They are a special type in the types of the forms of geomorphy of winddeposits.The viewpoints of predecessors researches on the causes of formation of pyramidal dunesare disputed vety much.By observing the pyramidal dunes in different places of Taklamakandesert,amd making typical amalysis for the causes of the formation of the pyramidal dune inOidoragh in the east of Yutian county,the author puts out the viewpoint of comprehensive causeof formation which contains necessary conditions and full conditions,amd comsiders that pyrami-dal dunes could be formed in any where if the conditions are fully satisfied,and the cnstruction ofall pyramidal duness in complex in combination,The condition of formation of pyramidal dunesare sources of various sizes sands in certain proportions,enough intensity of the flow of winddrift,and existence of winds in two direction which are nearly equilibrium and perpendicularcross,amd existence the circular movement of air introduced by updraft turbulemce by the differ-ence of pressure of inversion layer introduced by the surface of ancint and moderm reliefs,If thesefactorc coordinate just right in some place,the pyramidal dune could be formed. And to fully rec-ognizing the mechanism of the formatiom of pyramidal dunes is relafed to the amalysis,testingand verifing a large number of physic proccesses in deserts.