《徐霞客游记·粤西游日记四》
洞西裂开一条缝，下坠之处有个圆圆的洼洞，也不怎么深，分为两层而已。
其西裂一隙，下坠有圆洼，亦不甚深，分两重而已。
On the west, the grotto has a cleft where a round depression is located below, which is also not very deep, being only two stories high.