Chapter 1 Introduction to the geology of Myanmar

The Republic of the Union of Myanmar (Pyidaungsu Thammada Myanmar NaingNganDaw), formerly Burma, occupies the northwestern part of the Southeast Asian peninsula. It is bounded to the west by India, Bangladesh, the Bay of Bengal and the Andaman Sea, and to the east by China, Laos and Thailand. It comprises seven administrative regions (Ayeyarwaddy (Irrawaddy), Bago, Magway, Mandalay, Sagaing, Tanintharyi (Tenasserim) and Yangon) and seven states (Chin, Kachin, Kayah, Kayin, Mon, Rakhine (Arakan) and Shan). From north to south Myanmar extends for some 2000 km from 28° N to 10° N, with the Tropic of Cancer (23°30′ N) dividing the country into a temperate to subtropical north and a tropical south (Fig. 1.1). Although Myanmar is located within the Monsoon Belt of Asia, the climate is influenced locally by geographical position and topography. During the winter the northern mountains are influenced by cold air masses from Central Asia and are covered in snow for two months of the year. The mountains prevent cold air from spreading further south, so that most of Myanmar lies under the influence of the NE and SW monsoons. However, the north–south alignment of mountain ranges and valleys results in a pattern of alternating zones of high and low precipitation during both the NE and SW monsoons. Most precipitation comes from the SW Monsoon. Myanmar has three seasons, including: a dry summer from March to mid-May; a monsoonal rainy season from mid-May to September; and a cool winter season from October to February. The western coast of Myanmar is subject to occasional tropical cyclones such as Cyclone Nargis (2008) which, together with a storm surge, inundated the Ayeyarwaddy (Irrawaddy) Delta, killing an estimated 140 000 people, and Cyclone Giri (2010), which made landfall south of Sittway on the Rakhine coast, rendering tens of thousands of people …