Miaoli’s Huoyanshan (Mount Huoyan)

Huoyanshan (火炎山, literally Flame Mountain) is a famous natural scenic spot in Miaoli County, located at the boundary of Sanyi (三義) and Yuanli (苑裡) townships. It was once voted number one of Taiwan’s hundred must-visit trails by a hiking website. Huoyanshan is chiefly composed of shingle mixed with sandy soil. Continual weathering and erosion have produced cutting away and fragmenting of the terrain. And because the soil is rich in iron, the effects of weathering reveal colors of flame. In previous times, Huoyanshan’s trails were frequently used by Taiwan’s Pingpu indigenous people and Hakkas for settlement and commerce. Compared with other mountain trails in the country, they are not steep but they nevertheless test endurance.
Miaoli’s Huoyanshan
(Photo: Miaoli County Government)

Huoyanshan is located on the northern side of the Da’an River (大安溪) and is famous for its bare and towering landscape. The forest of Masson’s or horsetail pines is a rare sight in Taiwan. The Masson’s pine is a glacial relict, its needles slender and soft, and it is often known locally as the red pine. But how did it take root on Huoyanshan, where no grass grows? Originally, Huoyanshan’s badlands were only at the erosion area at the south face, the other two thirds of the area had good vegetation coverage and seldom collapsed, forming Taiwan’s most complete natural Masson’s pine forest. In order to preserve this rare and precious natural scenery from man-made interference, in 1986 Sanyi Huoyanshan was designated the first national nature reserve under the Cultural Heritage Preservation Act.

The geology of the Huoyanshan Nature Reserve belongs to the platform accumulation of the Quaternary period. It is the product of violent orogenic movements. Its rock formations consist of thick layers of shingle with thin layers of sandstone sandwiched between them, and their cohesion is weak. The continual effects of weathering and erosion function are the cutting off and fragmenting of the terrain. When you factor in the erosion from rainfall, the cut-away surfaces are extremely flat. This has produced the scenery of sets of sharp peaks and deep valleys filled with pebbles. If you stand to the south of Huoyanshan and look to the north, the view is even more magnificent. Sometimes there is no water in the south-facing mountain streams and large amounts of gravel accumulate in the estuary, producing a very special landform. In addition, the soil between the shingle layers, owing to the rapid effects of oxidation and leaching and the abundance of iron and aluminum substances containing oxides, between the deep valleys and the sharp peaks, give off bright red, gold, orange and brown colors. Especially at sunset, the whole mountain appears red like burning flames, and it is this that gives Huoyanshan its name (“flaming mountain”).
Because the soil is rich in iron, the effects of weathering reveal colors of flame
(Photo: Forestry Bureau, Council of Agriculture)
The northern side of Huoyanshan – the side that has not collapsed – is actually lush with greenery, but it often gets overlooked because the terrain on the southern side is so eye-catching. Huoyanshan is seemingly barren land, but behind it is full of vitality, an ecological treasure trove. For instance, every March and April when the northeast monsoon winds ease off, grey-faced buzzards that winter in the Philippines will ride the warm southwestern air current to Huoyanshan. They will remain at Huoyanshan to forage, creating interesting scenes.