Province of the Indian Empire, but geographically part of Indochina or Transgangetic India (later). It includes, since the annexation in 1886, the British territories of Upper and Lower Burma (Lower and Upper Burma), the indigenous states of the Shan (Northern and Southern Shan States) and Karenni, and various territories that escape administration in the more remote parts of the region.
The province extends between 9 ° 55 ‘and 28 ° 30’ of lat. N. and between 92 ° 10 ‘and 101 ° 5’ long. E., with an area calculated at 605,300 sq km, about double the size of Italy. One half of the territory lies outside the tropic, but its nature is such that it can be considered entirely as tropical. The Gulf of Martaban and that of Bengal, the Indian provinces of Bengal and Assam, Tibet, the Chinese province of Yün-nan, French Indochina (for a short distance) and Siam, form the borders of the province.
Burma can be divided into three major geo-morphological units: a) Arakan Yoma, a large series of folds, of Alpine age, which forms the barrier between Burma and India; its hilly expansions reach as far as the shores of the Bay of Bengal; b) the Shan plateau, which occupies the entire eastern portion of the country and extends south into Tenasserim: it is part of the Indo-Malay mountain system and has existed, as a geo-morphological unit, since the end of the Mesozoic; c) the central basin, between the two areas mentioned, formerly a gulf of the tertiary sea, now occupied by a vast expansion of tertiary land.
Geology and morphology. – The Arakan Yoma and its continuation to the north have a nucleus of old crystalline rocks, on both sides of which lie tightly folded sedimentary rocks, mostly of the Tertiary age. Jurassic and Cretaceous soils have also been reported, but the geology of the range is still poorly known; chromite and other useful minerals occur especially associated with serpentines, but are not exploited.
The western edge of the Shan plateau is well marked, both in the geological constitution and in the topography: it rises sharply from the valley and for 700-800 km. it is formed by a strip of granite or gneissic rocks. And gneisses are the prevailing rock on the plateau: from them come the rubies and other precious stones for which Burma has been famous for a long time, together with a compact limestone of the devonic-carbonic age. Lands of all ages, from the Precambric to the Jurassic, emerge from the high massif, while deposits from the Upper Tertiary and Pleistocene periods occupy old lake basins. In the precambric series of Mogok there are the main (open) mines of rubies, now however an industry of secondary importance; at Bawdwin, associated with a group of ancient volcanic rocks, are vast deposits of silver and lead minerals (mostly a galena argentifera), which are mined by Burma Corporation Limited and processed in nearby Namtu, from where the metal is brought by rail to Rangoon for export. Other similar deposits are known and were in the past used by the Chinese. Tenasserim is a continuation of the Malaysian Tin Belt and supplies large quantities of tin and tungsten. This portion of the Indo-Malay system consists of large granite intrusions elongated in a north-south direction and injected into a series of ancient rocks, the exact age of which is unknown. whence the metal is brought by rail to Rangoon for export. Other similar deposits are known and were in the past used by the Chinese. Tenasserim is a continuation of the Malaysian Tin Belt and supplies large quantities of tin and tungsten. This portion of the Indo-Malay system consists of large granite intrusions elongated in a north-south direction and injected into a series of ancient rocks, the exact age of which is unknown. whence the metal is brought by rail to Rangoon for export. Other similar deposits are known and were in the past used by the Chinese. Tenasserim is a continuation of the Malaysian Tin Belt and supplies large quantities of tin and tungsten. This portion of the Indo-Malay system consists of large granite intrusions elongated in a north-south direction and injected into a series of ancient rocks, the exact age of which is unknown.
The Irawady basin (Irrawaddy) is made up almost entirely of soils of the Tertiary, notable for their power: 5000 m can be assigned to the Eocene strata. thick, as or more in the Peguano (Oligomiocene), over 1500 meters in the Irawadian (Middle Pliocene). Aligned in the center of this basin are the well-known oil fields, mainly in strata of the Peguano: (from N. to S.) Indaw, Yenangyat, Singu, and Yenangyaung, which are the most important, Minbu and many other minor ones. In the Chindwin Valley and elsewhere there are hitherto little-used lignites; and along the center of the ancient Tertiary gulf many extinct volcanoes appear aligned, which in some cases form small tuff cones with lake-craters, in others they appear as mounds of Ryolitic materials. The largest is the complex cone of Myanmar Popa.
The bundle of chains that divides Burma from India has little width in the north and is known as the Patkoi or Patkai Hills; further south the direction becomes more decidedly meridian and the range widens, including the plateau of Manipur. It is from this, that is, roughly from the Tropic of Cancer, that the name of Arakan Yoma is applied to the chains: the plateau becomes narrower, it inflects to S.-SE. and ends at C. Negrais, although its geological continuation is represented by the Andaman and Nicobar Islands. A small part of Burma, Arakan, remains between the chains and the sea. Many peaks rise to over 3000m. and the tallest is believed to be Myanmar Victoria.
The eastern plateau, which also embraces the Shan states (v.), Is one with the great Chinese plateau of Yün-nan: it has an average height of 1000 m., But its surface is very incised and fractionated and flows through it, in a deep north-south incision, the Saluen (Salween). To the south in Tenasserim the plateau character is also gradually lost.
The central basin, which collects the waters of the Irawady, its tributary Chindwin and the smaller Sittang, is for the most part a lowland, with lines of hills stretching towards the meridian: of these the Pegu Yoma is the most important. Almost in the center, the Popa, an extinct volcano, as mentioned above, rises up to 1500 meters.
The Arakan coast has the so-called “Pacific” type: rocky and dangerous with the mountain leaning against it and fringed with islands. The largest are Ramree and Cheduba. Similar is the coast of Tenasserim with the Merghi Archipelago. Between the two coasts the low deltas of the Irawady and the Sittang widen.
The mountainous and hilly regions were originally covered by a dense forest and on large tracts have an excellent forest soil. Where the temporary crops have eliminated the forest, the original fertility has also disappeared and in the wetter areas the heavy rains tend to remove the loose soil, exposing the rock. The limestone areas of the Shan plateau are generally covered with a thin layer of “red earth”. The richest soils in the province are the alluvial ones of the Irawady delta and the wider valleys. An excellent marly soil is given by the sands and clays of the soils of the Peguano: but the Irawadian series and some others can give very light soils, almost pure sand. In the wettest areas of the province, due to the well marked dry season.