306 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1926 
of so large a part of the inhabitants of India. The country back 
from the Irrawaddy, in northern Burma, in the Shan States and 
westward toward the Arakan hills, is inhabited by various less- 
civilized peoples, each with its own peculiar dress and appearance, 
who come down to the river in picturesque groups to buy and sell 
when the market boats pass up and down on their regular sailing 
schedule. 
The country is rich in minerals. The great silver-zinc-lead deposits 
at the Bawdwin mines have been worked from the most remote 
antiquity. Tin and tungsten are of widespread occurrence in south- 
ern Burma. Coal occurs in many parts of the country, and the oil 
fields are large and highly productive. The greater part of the jade 
carved in China really comes from the Myitkynia district of Burma, 
where there are also large amber deposits. 
As will be seen in the accompanying sketch map (fig. 1) show- 
ing the main features of the geology of Burma, a long and generally 
narrow band of very ancient pre-Cambrian (Archean) rocks, having 
approximately a north-and-south direction, forms a protaxis running 
through the entire length of the country, passing across the border 
into China, and probably finding its farther continuation in one or 
the other of the narrow bands of Archean rocks shown in western 
Yunnan on the geological maps of southern China. This belt, com- 
ing up from Tenasserin, broadens out to the north of Mandalay and 
underlies the celebrated gem area of Mogok. 
This district is reached by taking one of the Irrawaddy River 
boats at Mandalay (pl. 2) and ascending the river where pictur- 
esque groups of native people await the arrival of the boat at every 
landing place (pl. 3). At Thabeikkyin, a point about 70 miles 
above Mandalay, a good motor road runs back from the river in an 
easterly direction for a distance of 60 miles to the little town of 
Mogok, near the border of the northern Shan States. This road 
starting from Thabeikkyin, which is 600 feet above sea level, rises 
at first slowly and then passes through a group of mountain ranges 
over a pass 5,000 feet high (pl. 4) and descends to the Mogok 
Valley, which has an elevation of 4,000 feet. The higher portions of 
this road afford a view in all directions over a veritable sea of moun- 
tains clothed with a luxuriant forest in which are magnificent 
flowering trees and many birds, the scene being one of extraordinary 
beauty. Much of this forest has been set aside for Government 
forest reserves. 
The isolated hill at Mandalay (954 feet), which rises abruptly 
from the plain on which the city is situated, is composed of a white 
crystalline limestone, rendered impure through the presence of 
grains of pyroxene, biotite, graphite, etc. It is identical in appear- 
