Mountain Ranges

Taiwan's five longitudinal mountain ranges, which are mostly forested, occupy almost half the island, with more than two hundred peaks over 3,000 meters. Steep mountains over 1,000 meters high constitute about 31 percent of the island's total land area, making for some of the island's most dramatic and beautiful scenery. As a group, the mountain ranges extend 330 km from north to south, almost the entire length of the island, and an average of about 80 km from east to west. The highest peak is Jade Mountain at 3,952 meters tall, which is also the highest mountain in East Asia.

Extending down the eastern half of Taiwan proper, the Central Mountains serve as the island's major watershed. The range is mostly composed of hard rock formations resistant to weathering and erosion, although heavy rainfall has deeply scarred the sides with gorges and sharp valleys. The Syue Mountains lie to the northwest of the Central Mountains, gaining in elevation as they extend southwards. The Jade Mountains—home to Jade Mountain—run along the southwestern flank of the Central Mountains. To their west are the Alishan Mountains, with elevations of mainly between 1,000 and 2,000 meters. The East Coast Mountains, located east of the narrow fault valley in east Taiwan, consist chiefly of sandstone and shale and are mostly composed of large hills.

Volcanic Mountains

Small outcrops of igneous rock are scattered over the island, representing at least five periods of igneous activity. While Taiwan's many volcanoes are either dormant or extinct, geothermal activity has produced many hot springs across the island. Popular for their reputed therapeutic properties, these springs attract tens of thousands of foreign visitors each year. The Datun Mountain area, known for its hot springs and fumaroles, is a prominent group of volcanic peaks lying across the promontory between Keelung Port and the Danshuei River.

Foothills

Taiwan's foothills form a narrow zone running mostly along the western edge of the island's central mountain ranges. This geologic area is relatively rich in coal and oil, and has therefore been mapped and studied extensively. Characteristic topographic features of the zone include low hills, longitudinal valleys, and broad fault scarps.

The foothill region located between Fongyuan (north of Taichung) and Nantou is the largest section of foothills in Taiwan. These foothills are separated from the Keelung-Miaoli foothills in the north by shallow geologic faults and are intersected by three major rivers, the Dajia, Dadu, and Jhuoshuei. The Sun Moon Lake Basin lying about 765 meters above sea level, is also included in the region. Prominent foothill belts in southern Taiwan include those between Chiayi and Pingtung, and the Hengchun foothills, which occupy most of the Hengchun Peninsula.

Terrace Tablelands

Below the foothills, Taiwan's terrain gradually reduces in height to tablelands of 100 to 500 meters. These thick deposits of sandstone gravel come mostly from eroded material that has been washed down from higher areas, though some gravel beds may have been deposited near the sea and then raised into flat-topped tablelands by recent tilting. The broadest tableland is the Taoyuan Terrace in northeast Taiwan. Next in size are the Houli Terrace in Taichung, the Dadu and Bagua terraces in Changhua, and the Hengchun Terrace in southern Taiwan.

Flora and Fauna

Taiwan's tropical-to-temperate spectrum of climatic zones and contrasting topographies has endowed the island with a rich diversity of flora and fauna. Some 70 species of mammals, 500 species of birds (40 percent of which reside on the island all year round), 90 species of reptiles, 30 species of amphibians, 2,700 species of fish, and 18,000 identified species of insects (including some 400 butterfly species) are known to inhabit Taiwan. The abundant plant life in Taiwan includes 610 species of ferns, 28 species of gymnosperms, and 3,600 species of angiosperms.

In springtime, emerald-green seaweed covers wave-worn rocks along Taiwan's northern coast. (Chen Yuan-ching, courtesy of the Tourism Bureau)

According to the Council of Agriculture (COA), around 27 percent of vascular plant species and 11 percent of animal species found on the island are endemic to Taiwan. The government established a research institute in 1992 to better conserve these species.

Perhaps the most famous Taiwanese species of fauna is the Formosan landlocked salmon. It is believed to have become trapped in the frigid mountain waters of central Taiwan during the last Ice Age when ocean levels dropped dramatically and the salmon could no longer migrate back and forth from fresh water to salt water. Overfishing and pollution have damaged much of the salmon's natural habitat, causing the distribution and population to shrink dramatically. In 1989, the COA listed the Formosan landlocked salmon as an endangered species in accordance with the Wildlife Conservation Act, and in 1997 the Taichung County government established the Formosan Landlocked Salmon Refuge in the upper reaches of the Dajia River in Shei-pa National Park.

As Taiwan lies close to the earth's most active tropical cyclone formation zone in the West Pacific, summer months are also marked by frequent thunderstorms and typhoons, with an average of three to four typhoons hitting Taiwan each year. Though strong winds and heavy rainfall can often cause severe damage, the storms are also a significant source of water, with windward mountain slopes sometimes receiving as much as 300 mm of rainfall in 24 hours. In 2006, four typhoons hit Taiwan, of which three—Bilis, Kaemi, and Bopha—made landfall along Taiwan's eastern coast. Typhoon Chanchu struck the Kinmen Islands before entering southern China.

Earthquakes

Taiwan experiences relatively frequent seismic activity due to its location on the circum-Pacific seismic belt and at the junction of the Manila and Ryukyu trenches along the west side of the Philippine Sea plate (PSP). However, most tectonic movement in Taiwan is weak and has no impact on people's lives. In fact, more than 95 percent of earthquakes cannot be detected without a seismometer.

The PSP and Eurasia plate (EUP) converge at a rate of about seven to eight centimeters per year. The convergence, which created the uplift that formed Taiwan's four central mountain ranges, continues its movement, putting most of the Taiwan area under a northwest-southeast compression. East of Taiwan, the PSP subducts northward beneath the EUP, while to the south of the island, the EUP underthrusts eastward beneath the PSP. Seismic activity in northeast and south Taiwan is associated with the two subduction zones. Activity in the rest of Taiwan is complex and less predictable. Geologists have identified 42 active faults on the island.

In central and west Taiwan, earthquakes are less frequent, of a smaller scale, and have a shallow focus. However, on September 21, 1999, a major earthquake occurred near Jiji Township in Nantou County, about 150 km to the south of Taipei, registering 7.3 on the Richter scale. It was the largest seismic event to affect Taiwan in all of the 20th century.

Sitting just off the southwest coast of Taiwan proper, Siaoliouciou is one of the largest coral islands in the world at 6.8 sq. km. Though not particularly well suited to agriculture, the island boasts unique coral formations brought into being by eons of wind and rain erosion. Much of the coral is a brilliant crimson as it is composed primarily of iron and silicon oxides.

Taiwan maintains a historical claim to the islands of the South China Sea. Four groups of vast area: the Dongsha (Pratas) Islands, Nansha (Spratly) Islands, Sisha (Paracel) Islands, and Jhongsha (Macclesfield Bank) Islands. Currently, Taiwan's effective jurisdiction includes the Dongsha Islands and Taiping (Itu Aba) Island in the Nansha Islands.

The Dongsha Islands are located about 444 km southwest of Kaohsiung and comprise Dongsha Island and two coral reefs. Dongsha Island is a coral atoll with a land area of 2.38 sq. km. In addition to being a source of fish and minerals, the islands are also used by Taiwan as a naval outpost.

The Nansha Islands consist of 180 islets, reefs, cays, and banks in an area extending 810 km from north to south and 900 km from east to west. Taiping Island, located 700 miles southwest of Kaohsiung, is the largest island in the group with an area of just 0.48 sq. km.

To the northeast of Taiwan proper is the Diaoyutai Archipelago, a tiny group of islets located 139 km northeast of Keelung City's Pengjia Islet and with a total land area of 6.3 sq. km.