The underground riverway had wide stretches and narrow stretches, creating all manner of unusual scenery below the earth.
The terrain came in a thousand shapes and strange forms, sights rarely seen aboveground. The forests of stalagmites and inverted spikes they passed through were a magnificent spectacle; standing among them felt like being inside the fanged maw of some monstrous beast. In certain special places, a torch's light refracted into dreamlike, dazzling colors.
"These underground riverways were all carved out by groundwater. The reason some parts are wide and others narrow has to do with how readily the geology dissolved under the flow of water. Areas that dissolved easily were naturally widened by the river's endless scouring over the years, while the narrow places were naturally those that did not dissolve easily..."
"A paradise of immortals? You're overthinking it. These stalactites formed when water containing carbon dioxide seeped into limestone and dissolved the calcium carbonate in it. You wouldn't understand even if I explained it. In short, water seeped through the limestone and dissolved some substance within it. When it dripped down, the water dried up, and the dissolved material solidified again. Drop by drop, over tens of millions of years, it accumulated into this. If you don't believe me, take a close look. See whether there are drops of water at the tips of those stone shoots..."
Faced with Shang Shuqing's astonishment at certain underground landforms, Niu Youdao could not bear the thought that such an intelligent woman could be so ignorant, and casually explained a little.
He walked ahead, pointing here and there at random as he explained. Yet Shang Shuqing was deeply moved. Following behind him and gazing at the back of his head, she said with a complicated look in her eyes, "Daoist Master, you know so