400 Journal of the Asiatic Society of Bengal. [November, 1913. 
and appearance from that which formed the walls of caves in 
the neighbourhood. 
iam, the whole of the great range on the west which 
h 
limestone beds are found throughout the Malayan 
Provinces and in the Ratburi district. The Chieng Mai district 
towards the north and west, and where the Mekong turns from. 
east to south they again appear as a barrier of ever-decreasing 
the junction of the Nam Mun and the main river the great 
of Central Siam. Limestone pinnacles are found piercing the 
alluvium of Central Siam, as at Chainat, Prabat, and 
Permo-Carboniferous limestones are known to occur in 
Sumatra, Toba-landan, Timor and Rotti2 In Western Borneo 
they contain caves which are very similar to the Burmese and 
Malayan ones. 
Further to the east in Tongking and the Laos, limestones 
of the same age have been identified. 
To the north of the Moulmein, Amherst and Thaton 
districts the limestones stretch through Karenni into the Shan 
States. Caves are found in them along the edge of the hills 
bordering on the Shan States and dividing them from the 
broad plains of the Irrawaddy valley. These caves are well 
known as they yield large quantities of bat guano.* In the 
The dark-grey limestone frequently weathers almost 
, into pin- 
nacled crags, weather-beaten towers and walls: into deep 
basins and swallow holes (often as regular and circular as 
1 W. A, Graham Siam, Lond 3 
: ’ , on, 1912, pp. 86-98. 
See literature quoted by J. B. Seri L 
Brit. Assoc. Reve 1993, p “oo es 
No ie urkhill, Guano in India, The Agricultural Ledger, 1911, 
