PRE-JURASSIC SEDIMENTARIES. 21 
ranges separating upper Chumbi and the Phari plain from Bhutan, 
These rocks consist of limestone, sandstone, quartzite, slate and 
shale ; limestone predominates, forming steep cliffs at Dothak and 
throughout the neighbouring ridges. Except in the immediate 
neighbourhood of the granite, where the rocks have been subjected to 
contact-metamorphism, the whole series is one of unmistakeably 
sedimentary origin ; the beds have a general northerly dip, thus pass- 
ing beneath the Phari plain, and so underlying the Jurassic slates 
which extend from near Kamparab to Phari dzong. 
Unfortunately only the most cursory examination could be made 
of this series, which appears to cover such a large area and to be at 
the same time of great interest. Among the hills above Dothak at 
about a mile to the east of the river a small stream has exposed a 
section, perhaps 1,500 feet thick, of what appear to be the middle 
beds of the series These consist of limestones below with 
arenaceous and argillaceous beds above ; they have all suffered con- 
siderably from crushing, and any fossils that the rocks may have origin- 
ally contained are now for the most part represented by fragments 
of crystalline calcite. Near the top of the section, however, casts of 
ammonites were found in a thin band of hard quartzite and a few 
fragments of bivalve shells in an indurated slate ; these were all quite 
undeterminable even generically, consequently the age of this part of 
the series is unknown, and can only be conjectured from observa- 
tions made on higher beds seen in a valley opening on to the Phari 
plain at a short distance to the east of Agang, and which are 
regarded as of liassic age (see p. 26). 
Although it was not found possible to examine the hills between 
the Dothak section and the valley east of Agang, yet from what 
could be seen from the road at Kamparab, it appears safe to 
conclude that there is a continuous series from the altered sedimen- 
tary beds in contact with the Chumbi granite up to the supposed 
liassic limestones. This series must therefore include at least part of 
the Trias, and since its total thickness must be several thousand feet 
it may extend even lower down in the stratigraphical scale, including 
( 142 ) 
