YINCHUAN, Dec. 5 (Xinhua) -- Thirty rock paintings featuring images of human faces, believed to be works in the Paleolithic Age, have been discovered in northwest China's Ningxia Hui Autonomous Region.

These paintings were found by Zhou Xinghua, former curator of the regional museum, on the bank of the Yellow River in Beichangtan Village in the city of Zhongwei, while surveying ancient cultural resources there.

The paintings of human faces, in the shape of circles, rectangles and squares, measure from 20 cm in length and 15 cm in width to 10 square cm. There are also head decorations in different shapes.

The rock paintings are on a mountain slope on the northern bank of the Yellow River. The paintings cover an area of about 40 meters long and ten meters wide.

Most parts of the mountain are covered by silt brought about by the swollen river. The 30 paintings on the top of the mountain can be seen as the water level declines, according to Zhou.