Map of Isan

The Luak ridge in morning fog with the Sonthi valley in front

The Phetchabun mountains (Thai เทือกเขาเพชรบูรณ์) are a mountain range in Thailand. Isan ( Isan /อีสาน also written as Isaan Isarn Issan or Esarn is the northeast region of Thailand. The Sonthi River (ลำสนธิ is a tributary of the Pa Sak River. The Thai Alphabet (อักษรไทย àksŏn thai) is used to write the Thai language and other minority languages in Thailand A mountain range is a chain of Mountains bordered by highlands or separated from other mountains by passes or valleys The Kingdom of Thailand (ˈtaɪlænd ราชอาณาจักรไทย, râːtɕʰa-ʔaːnaːtɕɑ̀k-tʰɑj It extends in a roughly north-south direction, and separates the broad Chao Phraya river valley of central Thailand from the Khorat Plateau of northeast Thailand. The Chao Phraya (แม่น้ำเจ้าพระยา is a major River in Thailand, with its low alluvial river plain marking the mainland of the country Central Thailand (Central Plain is a region of Thailand, covering the broad alluvial plain of the Chao Phraya River. The Khorat Plateau also Korat Plateau is a plateau in the northeastern region of Thailand, also called Isan. Isan ( Isan /อีสาน also written as Isaan Isarn Issan or Esarn is the northeast region of Thailand. The mountain range is named after the city of Phetchabun which is located in the mountains. Phetchabun (เพชรบูรณ์ is one of the northern provinces ( changwat) of Thailand.

Until recently the mountains formed a barrier between the two parts of Thailand - only the railroad from Bangkok to Nakhon Ratchasima and one highway crossed it. Bangkok, known in Thai as Krung Thep Maha Nakhon (krūŋtʰêːp máhǎːnákʰɔn) or Krung Thep ( for short is the Capital, largest Nakhon Ratchasima (นครราชสีมา naˡkʰon ˡraːtʃasiːˈmaː is a city ( thesaban nakhon) in the north-east ( Before the construction of the railroad in the beginning of the 20th century, the separation of the two parts of the country was even more distinct. The twentieth century of the Common Era began on

The highest elevation of the Phetchabun mountains is at 1820m above sea level at the Phu Hin Rong Kla National Park in the northern part of the mountain range. Phu Hin Rong Kla National Park is a national park located in the Loei, Phitsanulok and Phetchabun Provinces of Thailand. It consists of two parallel mountain chains, with the valley of the river Pa Sak in the middle. To the south the mountains end in the Khao Yai national park, and are continued to the east by the Dong Phaya Yen, Sankambeng and Phnom-Dongrek mountain chains. Khao Yai National Park ( Thai เขาใหญ่ is a national park in Thailand. Dong Phaya Yen ( Thai ดงพญาเย็น lit Jungle of the Ice Lord) is a mountain range in central Thailand. The Dângrêk Mountains ( Khmer regular script:, Chuor Phnom Dângrêk; Thai: ทิวเขาพนมดงรัก Thiu Khao Phanom

Geologically, the mountains consist of limestone, interfused with slate and sandstone. Geology (from Greek γη gê, "earth" and λόγος Logos, "speech" lit Limestone is a Sedimentary rock composed largely of the Mineral Calcite ( Calcium carbonate: CaCO3 Slate is a fine-grained foliated homogeneous, Metamorphic rock derived from an original Shale -type Sedimentary rock composed of Clay Sandstone is a Sedimentary rock composed mainly of Sand -size Mineral or rock grains. A few igneous rocks are also found: granite, basalt and porphyry. Igneous rocks (etymology from Latin ignis, fire are rocks formed by solidification of cooled Magma (molten rock Granite (ˈɡrænɪt is a common and widely occurring type of intrusive, Felsic, igneous rock. Basalt (bəˈsɔːlt ˈbeisɔːlt ˈbæsɔːlt is a common Extrusive Volcanic rock. Porphyry is a variety of Igneous rock consisting of large-grained Crystals such as Feldspar or Quartz, dispersed in a fine-grained

Several national parks, forest parks and wildlife reserves are located in these mountains. National parks in Thailand (อุทยานแห่งชาติทางบก are defined as an area of least ten square kilometres that contains natural resources In 2005 these were accepted by the UNESCO as a possible future addition to the World Heritage list. United Nations Educational Scientific and Cultural Organization ( UNESCO) is a specialized agency of the United Nations established on November 16 A UNESCO World Heritage Site is a site (such as a Forest, Mountain, Lake, Desert, Monument, Building, complex These sites include the Phu Hin Rong Kla National Park, Thung Salaeng Luang National Park, Phu Luang Wildlife Sanctuary, Phu Kradung National Park, Nam Nao National Park, Phu Khiao Wildlife Sanctuary and some forest parks. Phu Hin Rong Kla National Park is a national park located in the Loei, Phitsanulok and Phetchabun Provinces of Thailand. Thung Salaeng Luang National Park is a national park located in the Phitsanulok and Phetchabun Provinces of Thailand. Phu Luang (ภูหลวง Wildlife Sanctuary is a Wildlife sanctuary in Northern Thailand, located in the south of Loei Province. Phu Kradueng National Park (อุทยานแห่งชาติภูกระดึง located in Amphoe Phu Kradueng