Geology at Baxian is a story in two chapters. In the first chapter, this cliff face sat at or near sea level, and wave action did its patient work: rushing into cracks, expanding them with hydraulic pressure, grinding away the softer rock and leaving cavities behind. The Paleozoic and younger sedimentary layers that make up this section of Taiwan's east coast were susceptible to this erosion, and over time the waves cut and hollowed and shaped.

In the second chapter, the coast began to rise. Taiwan's eastern shoreline has been tectonically active throughout recent geological history, lifted by the ongoing collision of plates. The cliff moved upward, taking the sea caves with it. The waves retreated to a new, lower base level. What was once a marine environment became an elevated shelf — a wall of dry chambers above the crashing surf, open to the air, sheltered from the elements, overlooking the Pacific from a height no ocean currently reaches.

The caves are among the most significant prehistoric sites in Taiwan. Archaeological investigation of the Baxian complex has revealed evidence of Paleolithic — Old Stone Age — occupation, making this one of the earliest known locations of human habitation on the island. The people who sheltered here were not the ancestors of any single present-day group; Taiwan's prehistoric human history is complex, layered, and still being reconstructed from fragments found in sites like these.

More than ten caves were documented on the 100-meter-high cliff face, each of different size and depth. The artifacts recovered from them speak to a time when Taiwan's coastline was a different place: its sea levels, climate, and human geography all shaped by conditions that preceded the island's long history of settlement and resettlement by successive waves of peoples. Baxian is, in this sense, a threshold — the earliest door into Taiwan's human past that archaeological evidence currently opens.

In more recent centuries, the caves took on a different kind of significance. Their shelter and their position — overlooking the sea, dramatic and memorable — drew religious use. The caves were named for the Eight Immortals of Chinese mythology, the Baxian, whose imagery found its way into the site. Some caverns were converted to Buddhist temples; others became places to store cremation ashes, providing a kind of sanctuary in stone for the dead.

This overlap of prehistoric importance and living religious practice created a complicated situation. The Cultural Heritage Preservation Act eventually required that Taiwan's government reclaim the caves from private religious use to protect the archaeological integrity of the site. The process was long and contentious. On November 22, 2017, the Taitung County Government, the East Coast National Scenic Area administration, and the Changbin Township Office together recovered the last remaining occupied cave, completing the reclamation of all thirty caves in the complex. The legal effort to return a prehistoric site to public stewardship had taken a decade.

Stand at the base of the Baxian cliffs today and look up: the cave openings are dark punctuations in pale rock, each at a slightly different elevation, arranged in no pattern the eye can easily decode. The Pacific meets the cliff below, its waves doing in the present what waves did to this rock thousands of years ago — shaping, wearing, excavating. The process that made the upper caves is still making new formations at the current sea level.

Changbin Township, on the east coast of Taitung County, is not a widely visited stretch of Taiwan's coastline. It lacks the dramatic gorge scenery of Taroko to the north or the resorts of Kenting to the south. What it has is this: a cliff face where the geologic past and the human past are physically layered, one above the other, the older story literally higher than the newer one.