About 518 million years ago, in a shallow sea where Yunnan now stands on a high plateau, a sudden mud slide buried a community of soft-bodied animals so quickly that their outlines survived as fossils. Those fossils, found in the Maotianshan Shale near Chengjiang, are among the most important ever found, because they capture the Cambrian explosion, the rapid appearance of most major animal groups. They include early arthropods, worms with spiny legs and some of the oldest known relatives of vertebrates, preserved with details like eyes, guts and gills. The site is a UNESCO World Heritage Site, and a small museum and viewing area explain what scientists have found.
The place is a hill of ordinary-looking grey and yellow rock, and it takes some imagination to see its meaning. Visitors usually get a good look at the exposed rock layers and the displays, with specimens that look like tiny, delicate drawings pressed into stone. It is a good reminder that deep time is real, and that the plateau you are standing on was once beneath the sea.
The surroundings are lovely. Chengjiang sits beside Fuxian Lake, one of the deepest freshwater lakes in China, with clear water and green hills around it, and the county is roughly an hour from Kunming, the provincial capital, known as the City of Eternal Spring for its mild climate. The roads here are mostly good, with expressways between the cities and winding local roads between hills, farmland and villages. Yunnan's elevation, well over a kilometre and a half, means that days are mild and nights cool, and the best seasons are spring and autumn, though rain falls mostly in summer.
Be realistic about the logistics. Motorcycle use by foreign visitors in China is tightly regulated, so check licence and permit requirements long before arrival. For fuel, services and food, use the larger towns along the main roads, as the nearest listed town in the data, Shilin, is about 40 km away. Yunnan is known for its food, from rice noodles served in a bowl of hot broth, which locals call crossing-the-bridge noodles, to wild mushrooms in season. A bowl of those noodles after the fossils makes a very good day.