《水经注·卷十一》
我查阅过从前的记载，想弄清这个间题，大概当初这里发过山洪，漂下大木筏，堆在这地方，后来沙土淤积，变成了陆地，又兴工筑起城来。因为木材埋在地下，所以能经久不腐。
余考记稽疑，盖城地当初，山水渀荡，漂沦巨栰，阜积于斯，沙息壤加，渐以成地，板筑既兴，物固能久耳。
I have read the ancient records and wanted to find out the answer to this question. Probably there were mountain floods here at the beginning, and large rafts of wood were floated down and piled up in this place. Later, the sand and soil silted up and became land, and the city was built with construction work. Because the wood is buried underground, it can last for a long time without rotting.