Sculpturing of the Mountains. SI 5 
year into that part of the Indian Ocean 6,368,000,000 
cubic feet of solid matter. This material would in one 
year raise a space of fifteen square miles one foot in 
height. The weight of mud, etc., that these rivers 
bring down is sixty times that of the Great Pyramid 
of Egypt, or about six million tons.” 
The for egoing facts should prepare even the most 
unsympathetic to calmly consider the views of geolo- 
gists. It is surely most reasonable to explain the 
past by appealing to causes now in operation. It is 
equally unreasonable to call in the aid of catastrophes 
and exceptional conditions to explain what may be 
attributed to causes still in operation around us and 
with which we are familiar. We must, at the same 
time, keep in mind this fact, namely, that the causes 
we see at work at present may have, in the past, 
differed in intensity or in degree, though not in kind. 
For instance, it would be quite in keeping with facts 
to suppose that during the sculpturing of the Blue 
Mountains, the rainfall might have been much heavier, 
the rivers larger, and, therefore, the work done much 
more extensive than would be possible under present 
conditions. To explain some particular effects, we 
might even picture to ourselves an exceptional rain- 
fall, and atmospheric and electrical disturbances on a 
magnificent scale, such as has often been observed 
when volcanoes are in activity. But, granting all 
this, the principle is not affected — that the enormous 
ravines of the Blue Mountains are not the direct 
work of earthquakes, earth movements or cataclysm, 
