Yakou (), also known as Guanshan Pass () or Daguanshan Pass (), is a
mountain pass
A mountain pass is a navigable route through a mountain range or over a ridge. Since mountain ranges can present formidable barriers to travel, passes have played a key role in trade, war, and both Human migration, human and animal migration t ...
in
Taiwan
Taiwan, officially the Republic of China (ROC), is a country in East Asia. The main geography of Taiwan, island of Taiwan, also known as ''Formosa'', lies between the East China Sea, East and South China Seas in the northwestern Pacific Ocea ...
transversing the
Central Mountain Range
The Central Mountain Range is the principal mountain range on the island of Taiwan. It runs from the north of the island to the south. It acts as a barrier between the east and west coasts, hindering travel. The tallest peak of the range is ...
within
Yushan National Park
Yushan National Park () is one of the nine national parks in Taiwan and was named after the summit Yushan, the highest peak of the park.Taoyuan, Kaohsiung and
Haiduan, Taitung
Haiduan Township () is a mountain indigenous township in Taitung County, Taiwan. It has an area of 880.0382 km2, with a population of 4,224 as of February 2023. The main population is the Bunun people of the Taiwanese aborigines
Taiwan ...
.
Yakou is known its frequent
sea of clouds
A sea of clouds is an overcast layer of stratocumulus clouds, as viewed from above, with a relatively uniform top which shows undulations of very different lengths resembling waves on the sea. A sea of fog is formed from stratus clouds or fog ...
on the east side due to
orographic lift
Orographic lift occurs when an air mass is forced from a low elevation to a higher elevation as it moves over rising terrain. As the air mass gains altitude it quickly cools down adiabatically, which can raise the relative humidity to 100% and cr ...
from the Pacific Ocean. However, due to severe road collapses following
Typhoon Morakot
Typhoon Morakot, known in the Philippines as Typhoon Kiko, was the wettest and deadliest typhoon to impact Taiwan in recorded history. The eighth named storm and fourth typhoon of the 2009 Pacific typhoon season, Morakot wrought catastrophic d ...
in 2009, Yakou is currently inaccessible by car.
Occasionally, the character "啞" (''yǎ'') is used in place of 埡 since the latter is a rarely used character.
History
Initially, a path made by the Bunun people ran through Yakou. During Japan's occupation of Taiwan, the path was widened to better govern the aboriginal population in the mountains. After Japan left the island, the path was widened into the
Southern Cross-Island Highway
The Southern Cross-Island Highway (), also known as Provincial Highway No. 20, links Tainan City on the west coast to Taitung City on the east coast, on the southern section of the island of Taiwan. The road is long.
From west to east, the road ...
. Construction ran between 1968 and 1972, and construction workers established a campsite near Yakou; the site of the campsite became a
hostel
A hostel is a form of low-cost, short-term shared sociable lodging where guests can rent a bed, usually a bunk bed in a dormitory sleeping 4–20 people, with shared use of a lounge and usually a kitchen. Rooms can be private or shared - mixe ...
operated by the China Youth Corps.
After Typhoon Morakot in 2009, multiple sections of the Southern Cross-Island Highway collapsed from the heavy rainfall. Immediately east of Yakou, a landslide buried Daguanshan Tunnel's east entrance and its adjacent parking lot and destroyed 300 m of highway. Though not as heavily affected, the hostel closed down after the typhoon.
The section of the highway from Meishan to the west and Xiangyang to the east was closed to outside traffic after the typhoon and remains closed to this day. The highway is expected to reopen in 2021.
Geology
The rock around Yakou is primarily composed of a
stratum
In geology and related fields, a stratum (: strata) is a layer of rock or sediment characterized by certain lithologic properties or attributes that distinguish it from adjacent layers from which it is separated by visible surfaces known as ...
composed of
argillite
Argillite () is a fine-grained sedimentary rock composed predominantly of Friability, indurated clay particles. Argillaceous rocks are basically lithified muds and Pelagic sediment, oozes. They contain variable amounts of silt-sized particles. T ...
, another of
shale
Shale is a fine-grained, clastic sedimentary rock formed from mud that is a mix of flakes of Clay mineral, clay minerals (hydrous aluminium phyllosilicates, e.g., Kaolinite, kaolin, aluminium, Al2Silicon, Si2Oxygen, O5(hydroxide, OH)4) and tiny f ...
, and a third of
slate
Slate is a fine-grained, foliated, homogeneous, metamorphic rock derived from an original shale-type sedimentary rock composed of clay or volcanic ash through low-grade, regional metamorphism. It is the finest-grained foliated metamorphic ro ...
and
phyllite
Phyllite ( ) is a type of foliation (geology), foliated metamorphic rock formed from slate that is further metamorphosed so that very fine grained white mica achieves a preferred orientation.Stephen Marshak ''Essentials of Geology'', 3rd ed. I ...
. Due to the parallel planes of weakness present in the rocks, Yakou and the rest of the Southern Cross-Island Highway is very prone to landslides and failures even before Typhoon Morakot in 2009, and reconstruction has proven to be very difficult.