1G4 
liecords of the Geuloyical Sarnej/ of India. 
[voL. xnl. 
of soft sands and clays banked up against a “rigid trap axis,” I could appreciate 
the dynamical apj3ropriatoness of the expression, but not so, where the ranges 
consist of schists and massive limestones, and the very existence of a marked 
or strongly differentiated axis of a more rigid character is, to say the least, a 
matter of the purest supposition. 
Equally is Mr. Ball at variance both with Mr. H. P. Blanford and myself 
regarding the nature of the barrier at the outfall of Naini Tal: Mr. Blanford 
and myself both regarding it as a moraine, whilst Mr. Ball terms it a landslip ; 
and I may here remark that to “landslips” (so far as I can gather) all the 
Kumauu lakes arc, in Mr. Ball’s opinion, duo. 
As regai’ds the particular case of Naini Till, it may be seriously objected to 
!Mr. Ball’s view, that the barrier is not placed where the sides of the valley are 
steepest, nor is the slope sufficient to suggest such a cause. A general idea of 
the objection here taken by mo, may be gathered by referring to the sketch of the 
lake given in Mr. Ball’s paper; but it requires a personal knowledge of the ground 
to realize how much bolder the slopes are at other parts, where no obstructive 
landslips have descended, than at the actual outfall. It may be sngge.sted that 
the very descent of the “ slip” has itself lowered the slope, and modified the profile 
of the neighbouring ground, but I do not think such is the case either here or any¬ 
where else, and I merely allude to the notion, to prove that it has not escaped 
consideration. A few words will not bo hero out of place, touching the effects 
produced by a ‘ landslip ’ as contrasted with those due to a ‘ moraine.’ 
A landslip in its proper and original sense, is a somewhat rare phenomenon, 
(depending on certain conditions of surface, subsoil, and drainage), such as the 
‘ undercliff ’ in the Isle of Wight, and such cases as quoted in White’s ‘ Sel- 
boni'ue’, but which are rare in the Himalayan region, though not unknown in 
the Salt-range. The term is, however, also applied to one of the commonest 
phenomena in hilly regions, the descent from a steej) hill or chff, of a mass of 
rocky materials, detached paidly by frost perhaps in the first instance, partly by 
water and partly by gravity; the initial movement where the mass is consider¬ 
able being possibly in some ca.ses due to an earthquake. This being the sort 
of phenomenon considered by Mr. Ball as being the cause wherefrom all the 
Kumaun lakes have originated, it is necessary carefully to consider how far the 
conditions present in such cases resemble or differ from tho.se connected with 
moraines, and whether they are adequate to the production of the results attribut¬ 
ed to them. Such ‘slips’ as I now allude to may be broadly divided into two 
classes, namely, those which consist mainly of rocky fragments, detached from a 
steep hill aide, always moi’e or less angular and often of a large size, and ‘ slips ’ 
from ground where the rock is more sandy or argillaceon.s, and in which water is 
more or less the prime mover; the result being the descent, often very gradual, of 
a heterogenous mass of mud and stones, whose power of progression is regulated 
partly by the slope over which it moves, and partly by the amount of fluidity of 
the ingp’edients composing it. Slips of rock fragments of the first class are, as a 
rule, sufficiently obviously connected with the source whence they are derived, 
and stand usually at a considerable angle, the slope varying, however, with the 
