Apart from attracting numerous tourists, limestone caves in Thailand
are an important feature of its physical geography, more specifically its
sedimentary structures. To appreciate the wondrous view of the Tham Lot cave (cave
in northern Thailand), we must understand the features of such cave first. A
cave like Tham Lot has stalactites and stalagmites, also known as dripstones. Stalacites
resemble huge drips that hang from the ceiling, and stalagmites are somewhat
similar to stalacites but rise from the ground. All of these features of a
limestone cave are due to chemical reactions of sedimentary rocks.
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This is a picture of Tham Lot cave
Something
unique about Thailand is that it contains rocks ranging from as old as from the
Precambrian to the Quaternary. That is 4.6 billion years ago to 2.5 million
years ago! The Precambrian rocks are primarily distributed along the
northwestern side of Thailand, but they can also be found in some Eastern and
Southern parts. Thailand also contains rocks from the Paleozoic, Mesozoic,
Cenozoic (Tertiary and Quaternary) times. Moreover,
the most common group of igneous rocks in Thailand are granites. The distribution of the granites in Thailand
appear to age from east to west, Lower Triassic (252.2 million years ago) to
Late Cretaceous (100.5 million years ago) respectively. It is
quite amazing how we in 2014 can appreciate a rock from millions of years ago! The diversity of the ages of these
granites are thought to be caused by “metamorphism, tectonic
deformation, hydrothermal activities and simple cooling processes.” Although
they are not so common, mafic and volcanic rocks are also exposed in some parts
of Thailand. Although igneous rocks in Thailand are proven to be extremely old,
the limestone caves can easily steal anyone’s attention. However, learning
about the sedimentary and igneous rocks of Thailand can enhance one’s gratitude
towards the entire physical geography of the country.
References:
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