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Vietnam: Ho Chi Minh Trail: 1  Geophysical Structure

described by Khôi and Giói

Viêt Nam=Vietnam

In the dry season there is no problem, but in the rainy and stormy season, the rivers in sudden spate are really terrible because they can sweep away everything. (p.6)

In many places, it seems that mountains and forests are competing for their place with the narrow plains to reach the Eastern Sea. (p.8)

The most propitious time to visit Trụng Son is in the dry season, from October to March. [...] On the trunk of trees and on rocks, the heroic deeds of individuals and organizations are recorded. (p.91)

presented by
Michael Palomino (2013)


from: The Hô Chí Minh Trail; Hoàng Khôi and Thê Giói Publishers 2008; English translation; first edition 2001; second edition 2008; printed in Viêt Nam; VN - TG - 6.149-1

[The mountain range in Vietnam "Trụng Son Range" (Cordillera of Annam, Chaîne Annamitique)]

Map of Vietnam with it's provinces
Map of Vietnam with it's provinces [1]
Map of Vietnam, Laos, and Cambodia
                              with the mountani range of Trụng Son
Map of Vietnam, Laos, and Cambodia with the mountain range of Trụng Son [2]

Vietnam consists of a plain in the north, with mountains around it. These mountains go further to the South forming a "backbone" in the middle of Vietnam ending in the South in a great plain. Fantasies of geographers mean that this mountain range would form an "S" striving also today's Laos and Cambodia. All in all this mountain range is over 1,000 km long.

Jungle mountains of
                              Trụng Son mountain range in Vietnam
Jungle mountains of Trụng Son mountain range in Vietnam [3]
Ho Chi Minh Trail,
                              road and lorry
Ho Chi Minh Trail, road and lorry [4]

The Trụng Son Range (Trụng Son means "Long Mountain") lies in western Viêt Nam starting in the west of Nghê An [northern province]. It runs through central Viêt Nam as far south as Trung Bô [region between Nghè An province and the town of Da Nang] to the Lâm Viên plateau of Dác Lác province [with the capital town of Buôn Ma Thôl].

There are "thousands of mountain peaks", and the structure of this mountain range is more a chaos without system than a range. Also the kind of rock is very diverse with "various kinds of rock-granite, rionite, pebble stone, sandstone, clay stone, and limestone", and in the South there is "a large basalt plateau" with Di Linh, Bao Lôc, and Lâm Viên (p.1).

French geographers were a little bit studying this mountain range of Trụng Son and called it "Cordillera of Annam (La Chaine Annamitique) (p.1-2).

[Eastern flank with winds and climate from the sea]

The eastern flank of the mountain range of Vietnam is very steep with peaks of over 2,000 m and steep valleys with deep abysses - and with many rivers. Add to this there are winds from the sea.

The western flank is not so steep and has many plateaus spreading southwards to the Mekong River. This western part of the mountain range has got Lao winds.

[North and South of the mountain range]

North is from Lam River [vietn. Song Ca, flowing into the sea at Vinh] to Hai Vân Pass [near the town of Da Nang]. Climate is humid with primeval tropical forests, green the whole year. The mountain ranges are in zig zag, in parallel, straight or broken lines (p.2).

Map with Lam River (vietn. Song Ca)
                                and Vinh
Map with Lam River (vietn. Song Ca) and Vinh [5]
Map with Da Nang with Hai Van Pass
                                (vietn. dèo Hai Vân)
Map with Da Nang with Hai Van Pass (vietn. dèo Hai Vân) [6]

Viewed from the plain of Nghê (p.2) An [province in North Vietnam] and Hà Tinh [southern neighboring province of Nghê An] to the West, [the mountain range of] North Trụng Son appears as an agglomeration of high peaks (more or less 2,000 m high). The local people imagine it to be a continuous green wall on the horizon and call it the Giang Màn Range ([translated: Jiang screen] comparing it to a curtain hanging across the sky). (p.3)

[The mountains are higher to the West, Pu Lai Leng with 2,771 m]:

The narrow path on Pu Lai Leng is full of pointed rugged rocks, and abrupt slopes over 200 km deep. (p.3)

Map of Vietnam with Pu Lai Leng Mountain [7]

Phu Xai Lai Leng (known in Vietnam as the top Pu Lai Leng, also Pulaileng), is a mountain in the northern Truong Son range. The mountain peak is 2720 meters high and is located on the border between Vietnam (Nghê An province) and Laos (Xiengkhuang province). This is one of the dominant peaks of whole Southeast Asia in a surrounding terrain of above 1500 meters [web01].
Map of Vietnam with
                              Pu Lai Leng Mountain

South is Central Trung Bô and Tây Nguyên ending with the Lang Biang plateau in Lâm Dông province (p.2).

[Border line between Vietnam and Laos]

Some of the mountains form the frontier between Vietnam and Laos (p.2).

[There is a legend of arranging the border line with the strong woman Mu Gia]

The Kings of these countries agreed to settle the dispute through peaceful means: each country should designate a person who would leave his/her native land on the same day, at the same hour and head for the other country. The place where the two persons meet each other would be taken as the landmark of the frontier between the two countries. (p.4)

[A strong lady, Mu Gia, was running as fast as she could (p.4) and Mu Gia Pass is called in memory of her]:

Mu Gia (Dame Gia), a strong and sturdy woman of Van Lan who could walk as rapidly as flying, was entrusted with the important task. Mu Gia arrived at a pass of a high mountain (the present Phu-co-pi to be precise) (p.4), when she met her rival from the other country. Ever since then, the pass has become the southwestern frontier of Van Lang. In fact, the pass is located in the middle of Tân Âp land (i.e. in the Nghê An - Hà Tín region) and Thông Kham village in Laos. The Vietnamese call it "Mu Gia" (old woman) Pass in memory of the efforts of this legendary woman. (p.5)

[There are many caves and grottoes in this mountain system of Vietnam and Laos]

At the foot of the Mu Gia pass is a large region of rugged limestone, (Ke Bàng - Khe Ngang of Quang B́nh province). Then comes the great range of limestone mountains Se-Bang-Phai of Laos. To the east of Trụng Son many caves and grottoes are found. The most famous is Phong Nha cave. (p.5)

[Sandstone, granite and basalt are changing rapidly]

Travelers will find many exotic things in the last section of North Trụng Son. Whereas the Ke Bàng - Khe Ngang region is accessed with difficulty. From Khe Ngang to the Lao Bao Pass (in Quang Tri Province) is the region of sandstone hills spreading down to the littoral region.

The shape of the mountains is varied, here are granite mountains with pointed peaks and sloping flanks such as the Ba Rên, Côn Co, and U Ḅ, and there are fairly high, slab-stone peaks, such as the Cotarum, Pa-Sa-Nia or Dông Châu.

The tourist will also find an expanse of basalt soil on the flank of Trụng Son. It is not continuous but intersected by the slab-stone hills of North Trụng Son, and, unlike other places, basalt is found not only on the hills but also in the valleys. This is the Lao Bao - Khe Sanh region. (p.5)

[Lao Bao Pass as a place of French jails and fighting place during Vietnam War]

The Lao Bao Pass is the lowest in the Trụng Son range (only 350 m high). It bears the historic name of a site where Vietnamese revolutionaries (p.5) struggled fiercely but silently in the French colonial jails and where thousands of US expeditionary troops lost their lives during the Road No. 9 - Khe Sanh campaign. (p.6)

[Northern part: wild life in the northern part of the mountain range "Trụng Son"]

The structure of this mountain range in Vietnam is very complicated and only the natives know all details about it. And there is much of wild life to see:

Indeed, the structure of North Trụng Son is complicated and inextricably varied. On the Trụng Son, the traveler will meet innumerable caves and grottoes, passes and slopes; he will have to cross many streams, tunnels, deep rivers, and pine forests. On the flanks of Trụng Son he can stop at many hot springs (the temperature of some of them may reach 70ºC). These are the vestiges of volcanic craters. He can meet with the paths followed by elephants, the dark and deep dens of tigers and panthers.

In North Trụng Son, there are at least 200 streams or rivers over 10 km long with steep sloping beds; most of them flow rapidly to the Eastern Sea. They form slanted, narrow, short valleys. In the dry season there is no problem, but in the rainy and stormy season, the rivers in sudden spate are really terrible because they can sweep away everything. (p.6)

[Central part: wild life in the central part of the mountain range "Trụng Son"]

In Quang B́nh, Quang Tri and Thùa Thiên Huê, the Trụng Son is generally of over 1,000 m of altitude in the South. Yet, the Son Trà in the East of the Hai Vân granite mountain marks the end of North Trụng Son. Here Highway No. 1 from Huê to Dà Nang looks like a long tape of silk meandering across this mountain mass at an altitude of 500 m. Here lies the picturesque Hai (p.6) Vân Pass, both the land road and the rail way, now apparent now invisible, wind around the pass.

To realize all the primeval character of North Trụng Son and to reach  the inaccessible and deserted age-old forest, the traveler can follow the unexpected path from Cai Khanh in the West of Cau Hai to the valley of the Ta Trach river. Winding along the Nong River, wading across many streams, climbing up many hills, he will come to the Bac River. (p.7)

[Southern part: many mountain chains in the southern part of the mountain range "Trụng Son"]

But from the South of the Hai Vân Pass to Eastern Nam Bô is the mass of South Trụng Son. If the traveler looks at it from the national highway that runs along the coast, he will not have an accurate idea of it, because South Trụng Son is composed of several mountain chains, now in the North-South direction like those from Quang Nam to B́nh Dinh, now in the North-East-South-West direction like those in the high region of Khánh Ḥa Province: the chains of Chu-Young-Xin, Lang Biang, Brai An.

In many places, it seems that mountains and forests are competing for their place with the narrow plains to reach the Eastern Sea. Following Highway No. 1 the traveler will see the magnificence of South Trụng Son. For example the Ba Ná Mountain in Quang Nam, from the top of which he can have a panoramic view of all the plain from Dà Nang through the Son Trà peninsula to the Sa Huynh mountain. A little to the South-West are the Ngu Hành Son (Five Mountains): Kim, Môc, Thuy, Hoa, Tho (Metal, Wood, Water, Fire, Earth), and both imposing and poetic. The mountains south of the Ngu Hành Son are also amazing, with the Thiên (p.7) Bùt looking like a pen brush drawing on the white clouds and the Thiên Ân looking like a huge stamp pressing on the surface of the Trà river in Quàng Ngai Province. The Trà Khúc river flows in the dense forest of cinnamon and sugar cane, the characteristic agricultural products of Quang Ngai. (p.8)

[Legend of a studious poor provoking the building of mountains Thiên Bút and Thiên Ân]

Many beauty spots in Quang Ngai are actually natural scenic splendors but they are explained by popular legends. For the Thiên Ân Mountain, legend says that there was once upon a time an orphaned young man, very poor but very studious. A white-haired fairy took pity on him, and gave him the necessary equipment so that he might go to the capital to participate in the examination. Unfortunately, at this moment, the Trà river was flooding all over the region and the local population underwent a lot of suffering and privations. Taking pity on them, the young man told the locals to sit on the two ends of his carrying pole and brought them to the other side of the river. The burden was too heavy, the pole broke, and his pen, brushes, and stamps fell onto the banks of the river and were transformed into two mountains, the Thiên Bút and the Thiên Ân. (p.8)

[More about southern mountain range of "Trụng Son"]

Because of its particular geological structure, South Trụng Son, with its small plains, offers beautiful landscapes of mountain shapes and river courses right down to the coast. Generally speaking, the South Trụng Son range has many offshoots leading to the sea, many rugged ridge ways, and thick forests growing just in the middle of the plains. Looking from an airplane, South Trụng Son looks like a mass of plateaus occupying almost all the area of Central Trung Bô (p.8).

The coastal plains are considered the small and narrow hems of the sea. This huge mass of mountains contains on its surface all the large undulations, the big rivers that meander to the West, lakes, valleys, even swamps, as well as market places and villages. Therefore, to have a general idea, one usually associates Tây Nguyên with South Trụng Son. South Trụng Son in Central Viêt Nam is noted for its size and high mountain peaks, such as Ngoc Linh, the Chu-yang-Xin, the Bi Dúp, and the Vong Phu or the Chu-mu and Gia Rích mountains. These peaks are at an altitude of 2,000 m above sea level. (p.9)

[Highlands in the southern mountain range of "Trụng Son"]

One can also say that South Trụng Son is the Tây Nguyên plateau. In fact, a large region of highlands lies (p.9) behind the curb of the edge of South Trụng Son; it is composed of many plateau of different altitudes, such as the Kon Tum, the Pleiku plateaus in the North gradually rise up from 400 m to 800 m and then decrease in the Dác Lác plateau in the middle to 400 m. The Lang Biang plateau rises again to 1,500 m to look down the Do Linh plateau (only 400 m high) at the extreme end of South Trụng Son. (p.10)

[Flat areas in the southern mountain range of "Trụng Son"]

The flat areas of the Tây Nguyên region is covered by the basalt red soil alternated with slab stone or granite hills. Here and there some limestone mountain chains are found. The soil of the plateau is the most fertile and the richest in Viêt Nam. In the days of French domination, many (p.10) roads were built linking the provincial capitals in the plains and the coastal areas of Southern Trung Bô: from Quang Nam to Dac Dru, Dac Sút, Dác To to reach Kontum; from Pleiku to Buôn Ma Thuôt, then to Tây Ninhor to Saigon via Dà Lat; from Quàng Ngăi to Kontum (near the border with Cambodia, there is an attractive ecological reserve); Qui Nhon to Pleiku; from Nha Trang to Buôn Ma Thuôt; and from Phan Rang, Phan Thiêt to Dà Lat (p.11).

In general, the communication lines in Tây Nguyên - South Trụng Son are in a fairly good state and convenient. The aforementioned mountain mass forms a region of plateau and, at the same time, the edge of South Trụng Son touching on the Eastern Sea, thus giving Viêt Nam (p.11) the curved shape of the letter "S". The area of South Trụng Son is nearly 70,000 km2 with uncountable mountains and forests, which is inhabited by 30 ethnic minority groups. (p.12)

[Tourism in the mountain range: dry season between October and March - "heroic deeds" recorded]

The most propitious time to visit Trụng Son is in the dry season, from October to March. On both sides of Trụng Son, there is warm sunshine, the verdure of trees spreads everywhere. The visitor to the Ho Chi Minh Trail will see innumerable exotic things in all sections and tracks of the system. For example, underground caves warmed up for days with logs and plastered on all sides with clay for storing salt. Salt can be preserved for a long time without becoming wet. On the trunk of trees and on rocks, the heroic deeds of individuals and organizations are recorded. (p.91)

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Photo sources
[1] map of Vietnam with provinces arranged by Michael Palomino (2013): http://www.ezilon.com/maps/asia/vietnam-maps.html
[2] map of Vietnam, Laos, and Cambodia with the mountain range of Trụng Son arranged by Michael Palomino (2013): http://www.vietvet.org/visit/maps/mape.jpg
[3] jungle mountains of Trụng Son: http://my.opera.com/khanhlinh086/albums/showpic.dml?album=636857&picture=8693729
[4] mountains, road and lorry in the mountain range of Trụng Son: http://www.vietnamspirittravel.com/guide/ho_chi_minh_trails.htm
[5] map with Lan River (vietn. Song Ca) and Vinh: http://commons.wikimedia.org/wiki/File:Lam_%28Ca%29_River.png
[6] map with Da Nang with Hai Vân Pass, arranged by Michael Palomino (2013):
[7] Map of Vietnam with Pu Lai Leng Mountain: http://vi.wikipedia.org/wiki/Phu_Xai_Lai_Leng