By taking the formation of mud-rain and dust-rain and other mud "granular fine sand"

and the inlaying of fine mineral grain into coarse sand and other phynomena

as the sole characteristic for the formation of loess plateau caused only by the blowing and carrying of wind

and after checking each different periods'loess

which were formated for 2.5million years long

it was believed that the formation of the loess plateau was indeed the causes that the loess dust

which was carried by wind from west

met the moist airflow from east then continuously fell down then accumulated gradually

The loess layer accumulated this way

in which the structure appears frame touch

possessed fine aeration and permeability originally

later it is affected by the reproduction of vegetation

especially by the effect of root system of grass

the character is strengthened.This is the sole background and source for the accumulation of loess up to 100 meters and formulating the complete loess platcau--ancient soil under the natural condition.The soil and water loss violently

the main reason was human's destory on natural vegetation

thus it thoroughly destroyed the permeability and anti-souring of soil.So recent harnessing measures on loess plateau are forced to be"no-site-retain all precipitation"as the strategic goal

and adopt measures as "cereal crops are planted on plain and plateau land

forest and fruit tree are set on gullies

grass and shrub are located on hillside";and combining with the social and economic requirement

to arrange the reasonable land utilization and concrete productive measures.