Once on a rock-strewn slope of the eastern foothills of Helan Mountain, the writer of the present article happened on a stone axe which archaeologists later identified as an artifact of the Neolithic Age.

• 笔者在宁夏贺兰山东麓的乱石坡上，曾拣到一枚石斧，经考古学家鉴定为新石器时期的遗物。