MEMOIRS 
OF 
THE GEOLOGICAL SURVEY OF INDIA 
The Geology of the Provinces of Tsang and U 
IN Central Tibet. By H. H. Hayden, B.A., B.E., 
F.G.S., Superintendent, Geological Survey of India. 
INTRODUCTION. 
Until the despatch of the Tibet Frontier Commission in the 
summer of the year 1903, nothing was known of the geology of 
the area lying between the northern frontier of Sikkin and Nam 
Tso (Tengri Nur)^ At both of these limits fossiliferous rocks had been 
found, first on the south by Sir Joseph Hooker, who in 1849 discovered 
limestones, which he regarded as Tertiary in age, on the eastern shore 
of Tso Lhamo (" Cholamo "),^ a small glacial lake at the northern 
foot of the Drongkhya La, and subsequently, in 1874, by Pandit Nain 
Singh, of the Survey of India, who collected specimens of Omphalia 
trotteriY?Xm? at Nam Tso. Nothing, however, was known of the 
intervening country, until, shortly after the arrival of the mission 
at Kampa dzong, Mr. Claude White, Political Agent in Sikkim, 
forwarded to the Geological Survey a number of ammonites character- 
istic of the Spiti shales. With these were a few fragments of 
lamellibranchs, which were referred by my colleague, Mr. Vredenburg, 
to the family of the Rudistse. The importance of this discovery 
'"Nam Tso" is the Tibetan and " Tengri Nur" the Mongolian name for 
this lake ; since the lake is actually in Tibet the former name is preferable. 
^ Hividlayan Journals, II (1854), 177. 
' Rec. Geol. Surv. Ind., X (1871), 21. 
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