The Crescent Spring With regard to the long-existent riddle of the Crescent Spring,there are a lot of explanations.Some hold that the land in the neighbourhood might have been the former Danghe River Bend ,a part of Dunhuang Oasis. Owing to the drift of dues and the change of river-courses, a water system of its own was formes;and due to the low terrain, groundwater constantly replenishes the spring water, so the spting is always filles with water and never dries up even in drought, And because of the existence of underground watercourses,which connect with the spring and help the diversion of water, the water will not overflow even after long period of rain. This explanation seems to give the reason why the Crescent Spring does not vanish,but it by no means explains why the flying sand does not fall into the spring. Another theory goes like this : The Crescent Spring might have been a wind-eroded lake .The Taoist Priests who lived beside the Cresent Sping witnessed in person that the sand silding down from sand dunes was blown up by strong wind to the summit.This might have been one of the reasons why the Crescent Spring was not buried by sand.      The beautiful sight and the wonderful natural structure of the Singing Dunes and the Crescent Spring have added to their fascination. To know ,you must go!