242 THE GEOLOGY OF THE MALAY PENINSULA. 
the Burmese and Himalayan life-provinces in Ordovician times 
was removed, changes in the distribution of land and sea brought a 
true middle Devonian fauna into Burma, and later a widespread 
transgression of the Permo-Carboniferous ocean took place over 
those tracts of Asia lying’ to the north of Gondwanaland. These 
changes are heralded by a series of limestones and shales, perhaps 
passing conformably upwards into the Plateau Limestone of Devon- 
ian age, and containing upper Silurian fossils characteristic of the 
Bohemian or Hereynian type, whereas, as described above, the rock 
formations before this contained fossils allied to Northern and. 
Western European types. 
Devonian. 
The shallow-water beds of the upper Silurian period near the 
northern coast of Gondwanaland, now known in the Northern Shan 
States, and the deeper-water graptolitic shales of Yunnan further 
from the shore, were succeeded by a uniform thick deposit of 
dolomitic mestone, which forms a great area of plateau land, 
extending from Yunnan into the Southern Shan States, and probab- 
ly continuous with the limestones in which the guano caves of Moul- 
mein are situated. It extends an unknown distance 1n an easterly 
direction, covering a wide area in China. On the west, in the 
Northern Shan States, it extends to the edge of the Irrawaddy al- 
luvium, but to the north and south of this it is separated from the 
alluvium by a strip of Archaean rocks. In several places its thick- 
ness can be shown to be over 5000 ft. It is remarkably homogene- 
ous, and it is sandy to the touch and granular, although it is very 
pure, and not at all siliceous in reality. It has a brecciated and 
imtensely crushed appearance, perhaps due to the great earth-move- 
ments at the close of the Mesozoic, and perhaps to sinking of the 
rock into solution-cavities. It as non-fossiliferous, except at one 
place in the Northern Shan States, called Padaukpin, not more 
than one hundred square yards in area, where a rich middle 
Devonian fauna was found, with predominating Western European 
types, and at one or two places in the south and north of Yunnan, 
where there is a close resemblance to the Padaukpin type. It is 
unexpected to find this type of fauna, because, as mentioned above, 
the life in the north of our area changed, in upper Silurian times 
from the Western European type to that of America and Bohemia. 
However, the fossils cannot be regarded as necessarily typical of 
the Plateau hmestones, on account of their extremely local occur- 
rence. 
In Yunnan and China the Devonian limestones are more 
bituminous and shaley than in the Shan States and Malay Penin- 
sula. In East Yunnan pure limestones are the exception, and in 
Indo-China the pre-Carboniferous beds are all sandy, suggesting 
that the sea of that period was more shallow and less open towards 
the north and northeast, and the fact that the Carboniferous lime- 
Jour. Straits Branch 
