140 R. Pumpelly—Secular Rock-disintegration, 
out of the rock.* In other words, if filled with water they 
would have been lakes without outlets and with unbroken 
sides of rock. In some exceptional instances it was clear that 
systems of intersecting dykes had been less acted upon by the — 
basin-making process than the intervening rocks, and the 
basins were formed in these last. 
turing by glaciers. 
He says that where the bed of a glacier diminishes its angle 
of slope, the vertical pressure of the ice on its bed becomes 
greater, both owing to the lessened inclination and to the 
increased thickness of the ice, while farther down the incline 
the widening of the valley causes the ice to spread and conse- 
quently to diminish its thickness and pressure; the result being 
a rock-basin dammed by a rock-bar. 
While this may be admitted, with some reservations, as 4 
satisfactory explanation for many fiords and lochs cut in the 
declivities of a mountain range or of a steep coast, it is useless 
in regard to the lake-basins of flat countries, like Finland and 
ritish America. Geikie endeavors to use this hypothesis t0 
explain also the rock-basins observed by me in Central Asia; 
but it is still more useless here as an explanation, because there 
are absolutely no traces of glaciation in Central Asia, outside 
of the high mountain chains. These Asiatic depressions are 
rough and ragged, and the debris contained in them consists of 
ragged angular fragments of the local rocks, while the glaciated 
basins of America and Europe are smoothed and polished, 4 
the debris they contain consists of the rounded an scored 
material of the dri 
The basins of Asia were emptied by wind, and those of 
Northern Europe and America were emptied by ice, but the 
wind and the ice were only immediate agents employed in rap" 
idly emptying basins which had been long forming by a pr 
cess common to both—-the secular decay of the rock. I would 
thus seek the real cause, not in the unequal nature and action 
of the instrument, but in the unequal physical condition of the 
* Pumpelly, Geological Researches in China, Mongolia and Japan, pages 72, 9; 
26, Smithsonian Inst., 1866. 
+ Geikie—Great Ice Age, pages 351-352, D. Appleton & Co., 1875. 
