Ancient Giant Trees Found in Petrified Forest Park Thailand

Thailand, a country known for its cultural and natural wonders, is also one of the best destinations for geo-tourism. It is blessed with geological attractions – whether it’s museums, parks, or conservation sites. In fact, more than 830 geological sites have been discovered throughout Thailand recently (1).

If you like to explore natural landscapes, geological phenomena, and geo-heritage, Thailand will certainly not disappoint. Some sites are very well-known, such as the famous Petrified Forest Park – home of “the world’s longest ancient petrified tree.”

In this article, you’ll find fascinating information about the Petrified Forest Park and its ancient giant trees found there. We will give you a background on their discovery and significance. We will discuss how old, how big, and what type of tree they are. Plus, helpful travel information is provided to plan your visit.

What is Petrified (Fossilized) Wood?

Before we dive deeper into the Petrified Forest Park in Thailand, let’s start with what “petrified wood” is. Basically, it is wood that has turned into stone or rock, also known as fossilized wood. It is the fossilized remains of terrestrial plants. It is formed when plant material has been buried by sediment and protected from decay due to oxygen and living organisms. Minerals replace the plant elements during fossilization, turning them into stone and rock. The result is a fossil of the original wood material, often showing preserved details of the bark, wood, and structures. This whole process is called “Petrifaction.” (1, 12)

A Background on the Ancient Giant Trees Found in Thailand

The ancient fossilized trees were found in The Petrified Forest Park (formerly known as the Khao Phra Bat Forest Park) in Tak Province, Thailand. It is in the Mae Salid – Pong Daeng National Reserved Forest area, which is now a part of the Doi Soi Malai National Park (1, 2).

This area contains many interesting geological features. It is considered a sedimentary basin, covering parts of Ban Tak and Sam Ngao districts in Tak province. It is surrounded by chains of low hills to high mountains with the watershed in flat to undulating terrain. The Ping River (the main river) flows from the north through Chiang Mai Province, and the Wang River (the minor river) flows from the north via Lampang Province (5). This causes the areas of the Petrified Forest Park to be highly diverse.

When Was the First Discovery of Petrified Wood in Thailand?

The first piece of petrified wood (approx. 1 meter long) was discovered in October 2003 by villagers who live in the reserve forest in Ban Tak District, Tak Province. The petrified wood and the surrounding areas were then inspected by officials of the National Park, Wildlife, and Plant Conservation Department, under the administration of the Ministry of Natural Resources and Environment.

The fossil wood was excavated, and within the same year, it became known how big the ancient tree was. Interestingly, by 2006, the officials found many pieces of fossil wood scattered over 35 kilometers. Some pieces were found on the soil surface. In contrast, some were partially exposed and required further investigation. Due to the discovery, the reserve forest covering an area of 20 kilometers was established as “The Petrified Forest Park” shortly after (3).

Since then, many people, including general visitors and students, have been visiting the reserve forest. Between 60,000 and 100,000 people are welcomed there per year (3). This led the National Park, Wildlife, and Plant Conservation Department to collaborate with a construction company to design permanent buildings covering the sites. There is also an exhibition hall that shares the history and knowledge of the Petrified Forest Park, bolstering its geological importance and reinforcing its conservation.

A nature trail between each giant petrified tree site allows people to walk through the living forest to see the astonishing ancient trees. With all these findings and facilities, this site has become one of the most popular geo-tourism hotspots in Thailand and the world.

How Many Ancient Fossilized Trees Have Been Found in Thailand?

At present, there have been 9 giant fossilized trees found. But only 7 have been excavated to expose all of the wood to develop as tourist spots. The wood from the other 2 trees is still mostly buried.

Here’s a breakdown:

Map showing the location of the seven petrified woods in the Petrified Forest Park, Tak Province, Thailand (Ref: Edited from Google Earth 2022)
  • The first fossil wood is the largest one, located at the first site.
  • The second to fourth woods are broken into thousands of pieces.
  • The fifth and sixth woods are also cracked in some areas.
  • The seventh wood is very well preserved.
  • The eighth and ninth woods are not completely exposed, most of which are buried.

Moreover, there are many additional petrified kinds of wood that are still unexcavated within the area of the Petrified Forest Park. They are preserved by building temporary covers.

How Big Are The “Giant” Petrified Trees in Thailand?

Following the discovery of the giant ancient trees in Thailand, the officials found that the first petrified tree was approx. 4 meters wide at the base, 1.8 meters in diameter in the middle of the wood, and 21 meters in length of the trunk, not reaching the upper end. They used Ground Penetrating Radar (GPR), one of the most useful geophysical techniques, to inspect the length of all trunk parts. This found that another trunk of 30 meters had not yet been unexposed.

Is this Ancient Petrified Tree in Thailand the Largest in the World?

In 2005, the whole wood of the first tree was excavated, and a surprising result was found. The total length of the wood was 72.22 meters, which is considered the world’s longest piece of fossil tree (10). Interestingly, the tallest trees in Thailand today are only 60 meters long. They are Krabak trees belonging to the Dipterocarpaceae (tropical oaks) species (4).

Here’s a run-through of the size and condition of the other fossilized ancient trees (in different sites):

The second to fourth woods are cracked:

  • The second one is 31.30 meters long and 0.50 meters in diameter.
  • The third one is 33.50 meters long and 2.10 meters in diameter.
  • The fourth one is 42.40 meters long and 1.40 meters in diameter.

The fifth and sixth woods are cracked in some parts:

  • The fifth one is 22.20 meters long and 1.20 meters in diameter.
  • The sixth one is approximately 50 meters long (around 33.6 meters long and 1.5 meters in diameter). This is because the upper part (of about 20 meters) was dismantled without permission during the digging of a reservoir.

The seventh wood is very well preserved:

  • The seventh one is 38.7 meters long, 1.5 meters in diameter, and has very large buttresses at the base.

The eighth and ninth woods are still unexplored.

What Type of Fossilized Trees Were Found in Thailand?

In 2010, the Department of Mineral Resources assigned some officials and scholars to study the types of petrified trees. Eight specimens from seven sites were collected and examined using the botanical affinities (wood structure) technique. The study results of 8 petrified wood samples were classified into two groups (1).

This is where it gets technical:

Group 1:

The samples of petrified wood from sites number 1, 3, 4, 6, and 7 show that the anatomical characteristics of all woods can be identified to the fossil tree named Koompassioxylon elegans and closely related to the extant species in the present called Koompassia malaccensis, or “Thong Bueng (ทองบึ้ง)” (1, 5).

  • Genus: Koompassioxylon
  • Species: Koompassioxylon elegans
  • Botanical affinity: This fossil wood is comparable to the extant genus Koompassia of the family Leguminosae – Caesalpinioideae, a large and tall tree inhabiting moist areas in Southeast Asia. This petrified wood closely resembles Koompassia malaccensis inhabiting freshwater swamps in the peninsula of Thailand, Malaysia, Singapore, Brunei, and Indonesia. It is also one of the endangered species in Thailand.
  • Fossil distribution: The species Koompassioxylon elegans was widely distributed in the Malaysian archipelago (Neogene forests), West Bengal, and the Lower Siwalik Formation in India.

Group 2:

The samples of petrified wood from sites number 2 and 5 show that the anatomical characteristics of all woods can be identified to the petrified tree named Pahudioxylon sp. and closely related to the extant species in the present called Afzelia xylocarpa or “Maca Mong (มะค่าโม่ง)” (1, 5).

  • Genus: Pahudioxylon
  • Species: Pahudioxylon sp., or Afzelioxylon
  • Botanical affinity: The fossil wood is comparable to the extant Afzelia xylocarpa (syn. Pahudia xylocarpa) of the family Leguminosae – Caesalpinoideae. It is widely distributed in Southeast Asia, including Thailand, Laos, Vietnam, Cambodia, and Myanmar, in areas with 5-6 months of rain and about 1,000 – 1,500 millimeters of annual precipitation.
  • Fossil distribution: This species has been reported from many countries in Africa (Algeria, Ethiopia, Chad, Tanzania, and Egypt), India, and northeastern Thailand.

How Old Are the “Ancient” Trees in Thailand?

The Preliminary Investigation:

During the preliminary investigations, officials, researchers, and some scholars collaborated together. They examined the geological and geographical information of the area to search for more petrified wood.

Potassium-argon (K – Ar) was used as a “dating method” to estimate the age of sediment where the trees were found. The initial result was 0.6 ± 0.2 to 0.8 ± 0.2 million years (1). They concluded that the fossil wood dates back to 800,000 years ago (3).

In 2015:

However, in 2015, the Department of Mineral Resources collaborated with the Department of Earth Sciences, Kasetsart University, to determine the age of the sediment and the wood. They used the Thermoluminescence (TL) method in the two sampling areas of the Petrified Forest Park.

Interestingly, the result of the sediment from the two areas indicates a date between 22,000 – 54,000 years and 20,000 – 22,000 years, while the age of petrified wood from the 7th site measured approximately 120,000 – 129,000 years ago (1).

In 2016:

However, in 2016 it was argued that the age of the fossil trees should be measured at approximately 800,000 years. This assertion was based on the age of tektite found in ancient floodplain sediments associated with petrified wood (1). However, the age of the trees remains the subject of much debate. Whether it be 120,000 or 800,000 years, this matter requires further study in the future.

Is it the Oldest Petrified Tree in the World?

Therefore, this petrified tree in Thailand is not the oldest globally. While the world’s oldest fossil tree was unearthed and investigated in the Gilboa fossil forest in the Catskill Mountains in New York, dating back 385 million years (9).

Where to Find the Longest Ancient Petrified Trees in Thailand?

The Petrified Forest Park is located at village No. 7, Tak Ok Subdistrict, Tak Province. This is within the Mae Salid – Pong Daeng National Reserved Forest (the Doi Soi Malai National Park). This is a remote area (around 450 kilometers from Bangkok), so it is not super convenient to reach.

Therefore, the most suitable mode of transportation is a private vehicle. Traveling by private vehicle, you should drive through Highway No. 1 (Phaholyothin Road). The Park is located at the 443rd-kilometer milestone (about 2.5 kilometers from Phaholyothin Road) (6).

Petrified Forest Park Useful Information:

OpenMonday – Sunday, 08:00 – 17.00
Admission feeFree
FacilitiesUtilities, local guide, pet accommodation (cats and dogs), parking lot, service center for disabled people.
DirectionGoogle Map
NoteAll types of vehicles are prohibited from entering the area of the Petrified Forest Park

The Petrified Wood Museum (Korat Fossil Museum):

Besides the Petrified Forest Park, there is also “The Petrified Wood Museum (Korat Fossil Museum)” for those interested in learning geology. It is the only fossil wood museum in Thailand and is also one of only eight museums worldwide. (The other museums are located in the USA, Greece, China, and Myanmar) (8).

Inside, there are three main exhibitions:

  1. The Petrified Wood Museum
  2. The Primitive Elephant Museum
  3. The Dinosaur Museum – includes rotating exhibition sections showing every 15 minutes. Viewing the entire exhibition takes about an hour.

Visitors can get there by private vehicles only (no public transportation). The museum is located in Ban Krok Duean Ha, Mueang District, Nakhon Ratchasima Province (7).

Petrified Wood Museum Useful Information:

OpenTuesday – Sunday, 09:00 – 16.00 (Closed every Monday)
Admission fee50 baht for adults, 30 baht for students, 20 baht for students, and 120 baht for foreigners.
DirectionGoogle Map

Petrified Forest Park has Artifacts from Other Parts of Thailand

In addition to the Park and Museum mentioned above, a large number of fossils have been collected from Northern Thailand and other parts of Thailand – whether it be vertebrates, invertebrates, or plant fossils.

For example:

  • Phu Wiang Dinosaur Museum.
  • Sirindhorn Museum.
  • Thung Wa Ancient Elephant Museum.
  • Rock and Mineral Museum.
  • 150 million-year-old Stone Shell Museum.
  • Phu Kum Khao Fossil Excavation Site.
  • Krabi Power Plant Fossil Museum.


Although Thailand is a relatively small country, its geological resources are magnificent and diverse – making the country one of the best geo-tourism destinations in the world.

If you are curious or passionate about geology, ecology, and plant diversity from the past and present, then you should visit Thailand. Packed with natural wonders, it can become your hub for learning these subjects. And checking out the ancient giant trees at the Petrified Forest Park is a perfect place to start!

Like always, if you want to discover more about Thailand, stay guided with ThaiGuider. You might learn something you never knew about this unique country.

Did you enjoy this guide? If yes, then we are certain you’d also love our article on Naka Cave.


1. กรมทรัพยากรธรณี. คู่มือผู้เล่าเรื่องธรณี อุทยานแห่งชาติไม้กลายเป็นหิน จังหวัดตาก. [ออนไลน์]

2. นารีรัตน์ บุญไชย, วิไลลักษณ์ นาคศรี, Russell J. Gray และ ประเทือง จินตสกุล. “ป่าไม้กลายเป็นหิน จังหวัดตาก กับแนวทางการอนุรักษ์ทรัพยากรธรรมชาติและพัฒนาเศรษฐกิจ อย่างยั่งยืน จากการมีส่วนร่วมของชุมชน.” Proceedings of the 3rd National Meeting on Biodiversity Management in Thailand (June 15-17, 2016): การประชุมวิชาการการบริหารจัดการความหลากหลายทางชีวภาพแห่งชาติ ครั้งที่ 3 (มิถุนายน 15-17, 2559):  40–47.

3. Nareerat Boonchai, Paul Grote, and P. Jintasakul. “Paleontological parks and museums and prominent fossil sites in Thailand and their importance in the conservation of fossils.” Carnets de Géologie (2009): 75-95.

4. Marc Philippe, Nareerat Boonchai, David K. Ferguson, Hui Jia, and Wickanet Songtham. “Giant trees from the Middle Pleistocene of Northern Thailand.” Quaternary Science ReviewsVol. 65 (April 1, 2018): 1-4.

5. Wickanet Songtham, Dallas C. Mildenhall, and Benjavun Ratanasthien. “Petrified Tree Trunks from a Gravel Deposit, Ban Tak Petrified Forest Park, Ban Tak–Sam Ngao Basin, Tak Province, Northern Thailand.” J Sci Technol MSU Vo. 31, No.1 (June – February 2012): 93-100.

6. Thailand Tourism Directory. อุทยานแห่งชาติไม้กลายเป็นหิน [online]

7. Museum Thailand. พิพิธภัณฑ์ไม้กลายเป็นหิน ซากดึกดำบรรพ์และไดโนเสาร์ [ออนไลน์]

8. We Korat. พิพิธภัณฑ์ไม้กลายเป็นหิน โคราช ของดีน่าสนใจที่มีอยู่เพียง 8 แห่งทั่วโลก. [ออนไลน์]

9. Science Daily. Oldest fossilized forest: Entire fossil forest dating back 385 million years unearthed [online]

10. Bangkok Post. Thailand seeks world record for petrified wood [online]

11. Live Science. Ancient Giant Trees Found Petrified in Thailand [online]

12. Geoscience News and Information. What is Petrified Wood? [online]


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