Sheshan is the only mountainous landscape within Shanghai's urban area, and also a rare volcanic relic in eastern China's plains. Sheshan consists of two mountain peaks, Dongshe Mountain and Xishe Mountain, with a Moon Lake creek flowing between them, forming a scenic line in Sheshan National Forest Park. There are four main types of rocks in Sheshan: rhyolite, tuff, breccia, and diorite porphyrite.

Rhyolite formed from cooled and solidified lava during volcanic eruptions, featuring a fluidal texture and vitreous quality. The fluidal texture refers to the streaky or wavy structures formed as the lava flowed, reflecting the flow direction and speed. The vitreous quality means the lava cooled rapidly without forming crystals, usually appearing black or dark colored.

Tuff is a sedimentary rock formed by compaction of volcanic ash, debris, and cementing material. Tuff is characterized by containing volcanic clasts of different sizes and shapes, such as breccia, crystal shards, glass shards, etc., often in gray or light colors.

Breccia is a sedimentary rock consisting of volcanic clasts and cementing material. Breccia contains abundant angular or irregular volcanic fragments in various sizes, often in black or dark colors.

Diorite porphyrite is a mixed rock comprising diorite and porphyrite. Diorite is an intrusive igneous rock with a porphyritic texture of phenocrysts and groundmass, usually dark gray or black. Porphyrite is a metamorphic rock made of coarse-grained crystals, often white or light-colored.

In addition to the four rock types, Sheshan also features various geological structures and phenomena like intrusive dykes, reverse faults, spheroidal weathering, and columnar joints, reflecting Sheshan's complex geological history and changes. Sheshan is not only a scenic spot with beautiful scenery, pleasant climate and rich ecology, but also an educational base for geology exploration, learning and research. I hope you have the chance to experience Sheshan's charm in person.

文 | Tim Shen, Allen Wang, Alpha Ye (G11)

排版 | Jang