How did nine streams and eighteen streams form?

Jiuxi Shiliu is located at the foot of Jiguanlong by the West Lake in Hangzhou, Zhejiang. On the one hand, the upper end starts from Longjing, on the other hand, it is connected with the third cave in Xia Yan, and on the other hand, the lower end is connected with Qiantang River, 7 kilometers up and down.

The water of Jiuxi originates in Yang Meiling, and flows into the waters of Wanqing, Hongfa, Fang Jia, Shi Fo, Baizhang, Tangjia, Xiaokang, Yun Qi and Zhutou along the way, hence the name Jiuxi. These nine streams all the way through the forest around their feet, and I don't know how many streams have merged into them. "Nine" and "eighteen" mean more.

The geological composition of Jiuxi Eighteen Rooms is basically sandstone. The hillside is steep, the bedrock at the bottom of the valley is exposed, the sandstone accumulation is small, and the water is shallow and clear. The water contains sulfur substances, so even if the weather is cool in autumn, you won't feel chilly when wading.

Professor Li Siguang, a famous geologist in China, is very interested in the geology of Jiuxi Eighteen Rooms. /kloc-in the winter of 0/947, Li Siguang came here twice and found the remains of ancient glaciers. He believes that in the Quaternary (about 1 10,000 to 23 million years ago), Hangzhou West Lake was once a world of ice and snow. At that time, Xialongjing was an ice-storage Pangu, which suffered a lot of ice and snow and passed through nine streams and eighteen streams to the southeast. Therefore, the glacier remains within 3 km from Xialongjing to Jiuxikou are clearly defined, and the whole glacier phenomenon is very complete, resulting in the dangerous terrain of Jiuxi and Eighteen Rivers. Yu Yue, a scholar in Qing Dynasty, left a poem after visiting Jiuxi, saying, "Jiuxi has eighteen streams, which is a beautiful place in the mountains. I have heard about it for a long time, but now my interest in it is poor. There are many overlapping mountains and winding roads. Dongdong is full of top, under the tall tree. "