Page:Provincial geographies of India (Volume 4).djvu/72

56 patches are younger than the underlying massive limestone, and correspond to the middle and upper Permo-Carboniferous of the Salt Range in the Punjab and of the Ural Mountains. The most significant points are the identity of many of the species with central Himalayan fossils, and of a few with Malayan forms, and a closer resemblance of the fauna to that of America. The Permo-Carboniferous ocean of the Shan States seems to have been connected in one direction with that of Malaysia, and in another direction with that of the central Himalaya and America.

During the next phase the coral reefs of the Devonian and Permo-Carboniferous, at least in the Shan States, were raised by a gentle earth-movement, which caused the sea to retreat leaving a land surface subject to the denuding agencies of the atmosphere. This land phase in the Shan States lasted throughout all but the lower part of the Permian and all but the uppermost part of the Triassic periods. Towards the end of this phase we find evidence of sea along the west of Burma, occupying what are now the Arakan Yoma and the Naga Hills, and to the north in Yunnan where the presence of beds of salt and coal points to shallow water conditions. After the coral-reef land of the Shan States had been worn by rain, rivers and other natural agencies into ridges and hollows, a gentle depression of the whole caused an invasion of the sea, which filled up the hollows with fine sediments. Some of these hollows maintained a connection with the open sea while others seem to have been more or less completely cut off as salt lakes. The amenities of aquatic life, therefore, varied considerably, and we find in some localities badly developed, stunted forms typical of restricted conditions, and in more salubrious spots well-favoured massive forms. These fossils have been identified as belonging to the uppermost Trias (Rhaetic stage), and a similar fauna has been found to the north in Yünnan and to the south in the Malay States and Sumatra.