Haflong Fault the south-westward continuation of the Disang thrust from the Naga Hills to Haflong where the thrust becomes a narrow but complex fracture belt. The westward continuation of this fracture belt ultimately passes into the Dauki fault. The behaviour of the different parts of this fracture belt, however, is not quite clear. Near Haflong the fracture zone changes its direction from northeast to southwest to nearly due west. About 60-km west of Haflong the Dauki fault appears to be a nearly vertical break and the beds on the two sides show no great difference in age. Further west downthrown is southerly and still further west in Garo Hills the fault heads to the north along which the shillong plateau has been shifted southwards.
In Haflong thrusting area, there is much variation in the structure of the south dipping monocline. In the east, between Haflong and Dauki, the beds north of the fault are mostly horizontal or dip gently down to the south, while those of the south of the fault dip more steeply and in places are nearly vertical. There is extensive shattering in a belt several kms wide along the fault. West of Haflong, where the fault has little stratigraphical throw, the geosynclinal facies of the Eocene approaches within seven kms of the Kopili beds which are part of the calcareous shelf facies of the Eocene, and which immediately overlie the Sylhet Limestone. It is inconceivable that these two utterly different facies of the Eocene could have been laid down within a few kilometres of each other without showing clear signs of transition from one facies to the other. [ASM Woobaidullah]