$5 HAYDEN : GEOLOGY OF THE PROVINCES OF TSANG AND U. 
in detail ; this is to be regretted since the relation of the Alveolina 
limestone to the underlying beds has not been ascertained, but the 
probable stratigraphical conditions are shown in the section on 
PI- 3, fig. 3- 
The Alveolina limestone crops out on the Dzongbuk La, in the gap 
between the two ridges of the Kampa-Tatsang range; it is overlain by 
a considerable thickness of dark shale, which forms the lower slope 
of the northern ridge ; this is overlain by limestone followed by sand- 
stone, the line of junction being apparently the continuation of the 
fault referred to above (p. 49). The ridge is capped by limestone 
with Radiolites and it appears therefore that the beds lie in a reversed 
fold (see PI. 3, fig, 3). 
The Alveolina limestone is underlain by a series of shale and 
limestone^ but this part of the section was not examined in 
detail and part of it is doubtful ; the beds on the upper part of the 
southern ridge are the upper Cretaceous (maestrichtian) limestone 
and the ferruginous sandstone. It is probable therefore that the 
doubtful part of the section includes the lower part of the Tertiary 
system as described above from the section close to Kampa dzong and 
the shales which underlie the Alveolina limestone probably represent 
the sandy and micaceous beds above the Orbitolites limestone. 
The Alveolina limestone and the overlying shales would in that case 
be younger than any beds seen on the section previously described. 
A curious feature of this series of Tertiary beds is the apparent 
absence of nummulites, which have not been recognised among 
the many forminifera found in almost every horizon from the base 
of the Gastropod limestone to the top of the Dzongbuk shales.' 
The total thickness of the beds enclosed between these limits must 
be almost, if not quite, 1,000 feet, and there can be no doubt that they 
all belong to the eocene series, whilst the absence of nummulitic lime- 
stone may possibly be due to the fact that that stage had not yet been 
' This name may be temporarily given to the shales which overlie the 
Alveolina limestone on the Dzongbuk La. 
( J77 ) 
