The Geology of Burma - Zomi Online Library

Bibliography of Burman Earth Science
extension, is a line of extinct volcanoes with small crater lakes and eroded cones. The
largest of these eroded volcanic cones is Popa Hill, at 1,518 meters (4,981 feet).
The coastal areas consist of the narrow Rakhine and Tenasserim plains, which are
backed by the higher ranges of the Rakhine and Tenasserim mountains. These coastal
regions are fringed with numerous islands of varying sizes.
As to economic geology, Burma is rich in certain minerals, including metal ores,
petroleum, and natural gas. Deposits of silver, lead, zinc, and gold are concentrated in the
northern Shan Plateau; tin and tungsten in the Tenasserim region, and barite around the
town of Maymyo in the central basin. Copper mining at the town of Monywa began in
the early 1980s and has been growing, despite intermittent setbacks caused by shortages
of fuel and supplies as well as by economic sanctions imposed by foreign governments.
Large-scale exploitation of Burma’s mineral deposits began in the mid-1970s.
Although production generally has been increasing since the late 20th century, mining
accounts for only a tiny fraction of the country’s GDP and a comparable portion of the
workforce.
The country also has significant deposits of precious and semi-precious stones.
Burmese rubies are internationally known for their deep color and quality. The country
also produces smaller quantities of spinels 2 , diamonds, and other gemstones.
Weather and Climate
Although Burma is located in the monsoon region of Asia, its climate is greatly
modified by its geographic position and its topographical relief. The cold air masses of
Central Asia bring snow to the northern mountains for two months of the year, but this
mountain wall prevents the cold air masses from moving farther south, so that Burma lies
primarily under the influence of the monsoon winds. The north-south alignment of ranges
and valleys also creates a pattern of alternate zones of heavy and scanty precipitation
during both the northeast and southwest monsoons. Most of the precipitation, however,
comes from the southwest monsoon. The west coast is subject to occasional tropical
cyclones.
Most of Burma lies between the Tropic of Cancer and the Equator. The Tropic of
Cancer divides the country into two regions: the tropical south that covers two-thirds of
the country, and the sub-tropical and temperate north, which is the remaining one-third of
Burma. This causes two distinct seasons: the dry season from mid-October to Mid-May,
and the wet season. There is a cooler spell during the wet season from December to
February.
The coastal regions and the western and southeastern ranges receive more than
200 inches (5,000 mm) of precipitation annually, while the delta regions receive about
100 inches (2,500 mm). The central region is not only positioned away from the sea but
also on the drier, lee side- in the rain shadow- of the Rakhine Mountains. Precipitation
gradually decreases northward until in the region’s dry zone it amounts to only 20 to 40
2 Probably named from the Latin word "spina", (meaning "thorn"), for its pointed (octahedral) crystals.
Spinel is a hard mineral with octahedral crystals found in igneous and carbonate rocks. Spinel occurs
typically as a contact metamorphism of impure dolomitic limestone, and less commonly as an accessory
mineral of basic igneous rocks. Spinal also occurs in alluvial deposits. It consists essentially of alumina and
magnesia (MgAl2O4), but commonly contains ferrous iron and sometimes also chromium. It is found in a
variety of colors including blue, green, brown, black, and the valuable red variety which resembles a ruby,
and is frequently used as a gemstone.
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