Oyster beaches are made up of remnants of oysters dated 5,800 to 2,200 years ago. The largest oyster beach is in the riverway between Shizhuang Zi and Jiangzhuang Zi, in Dongji Town in the western part of Ninghe County. It occupies 73 hectares. The thickest oyster beach is in Fei Zhuang near Jingshan Railway in eastern Ninghe County. Here, the layer of oyster shells is about five meters thick, and oyster shells account for more than 90% of these remnants. The diameter of the largest oyster shell, which is related to the rate of growth of the oyster, can reach 50 cm, while the smallest may be several centimeters.