PART 4.] 
Oldham: Note on the Naim Tal Landslip. 
:2Sl 
Yet it must always be kept in mind tbat no theory which can be put forward 
to account for their formation can be considered satisfactory, unless it also 
accounts for the absence of similar lakes in other parts of the Himalayas ; for it is 
no explanation to say that this is due to the smallness of the drainage areas which 
supply the lakes, and the consequent small size of the streams flowing fi-om them, 
for other portions of the Himalaya are not devoid of small streams, nor can that 
winch flows from Mulwa Tal be called small. 
NOTE. 
My youngest colleague, Mr. Eicliard D. Oldliam, happening to be in Kumaun at the time, 
I asked him to give me an account of the disastrous landslip at Naini Tal. The foregoing ex¬ 
cellent paper is the result. It is Mr. Oldham's first contribution to the publications of the 
f'urvey ; and the accurate observation, strict reasoning, and good form it evinces, give high promise 
of fi'uitful work to come. 
It will not he amiss, on an occasion of such vital interest, to add a few remarks that occur to 
me, especially as suggested by the report of the Committee appointed by the lioenl Government 
to enquire into the condition of the ISherka-dauda hill, a copy of which was sent to mo officially 
at about the same time, ‘for information. ’ ITie portion of the hill marked by the Committooas 
presently dangerous corresponds very ne.arly with that indicated by Mr. Oklliam j hut tlieir ob¬ 
servations would seem to have a wider extension, and to involve a larger area of affected ground. 
Mr. Oldham was only there for a few days, on his way to take up work for the season in Sirnuir, 
and lie probably coulined his attention to the particulars of the event under discussion. I did not 
instruct, or expect, him to do more than ho has done, the Survey not having been called upon for 
an examination of the ground. 
It would ho understood from the report of the Committee that the surface cracks, justly 
regarded us symptomatic of failing ground, occur much beyond the area condemned, also the Com¬ 
mittee’s description of the geological structure of the hill would he taken in the same sense; it is 
as follows :—“To the ordinary observer the hill seems to consist of a core of rocky shale, the dip 
of tlie strata being to the south-west, at an angle varying from 30° to 50°. This core is covered by 
varying thicknesses of disintegrated shale and mud, in which are scattered boulders of limestone, 
and oci asionally of trap, the whole of this crust being in its natural state bound together by a 
luxuriant growth of grasses, shrahs, and trees.” It does not appear that this is thought an unusual 
composition for the crest of a steep ridge, 7,000 feet in elevation. As applied to the dangerous 
ground, it would exactly suit the conditions described by Mr. Oldham—the decomposed clay-slate 
creeping down the hill side, carrying with it blocks detached from the occasional outcrojis of harder 
rocks. It is scarcely possible under the cireuni.stanees thatsnch a crust could be rock in situ, whether 
an enveloping shell of some uiiconformable deposit, or a condition, however decomposed, of tlie rocks 
described ns the ‘ core.’ It can, in such a position, only have been formed from these latter by 
displacement, being cither the remains of an old landslip, or the material in order of active 
preparation for a slip to come. In the former case the ground may be perfectly safe, in the latter 
it would he at least doubtful. If, then, this description applies extensively, as might be inferred 
from the Committee’s I’eport, the matter may he worth further consideration j for the premonitory 
‘ bulging,’ BO effectively detected and described by Mr. Oldliam, may not he a necessary part of the 
jierformance. In the case of the condemned area, that feature is reasonably ascribed to the 
resistance so well presented at the base, where the slope tails off into the flat ground at the head of 
the lake; hut where this condition docs not obtain, us along the lake shore to the sonth-east, 
a crisis might occur without that visible warning, although there would be every reason to expect 
it to be mild in comparison to what happens wlien an accumulation has occurred by bulging. 
Altogether, it is liy no means unreasonable to hope that the iiractieal judgment of the Com- 
