WATER IN THE ARCHITECTURE OF NATURE. 479 



the eye, and where the stifling heat and dust of sum- 

 mer alternates with the blinding snow drifts and the 

 rigours of an absolutely arctic winter. 



The paramount influence which water has exercised 

 in the architecture of Nature can hardly be overesti- 

 mated. From the dawn of creation, its mighty operations 

 have never been suspended even for an instant. From 

 age to age it has been gradually levelling down the 

 mountains, excavating the valleys, spreading out the 

 plains and table-lands; while its march towards the 

 ocean is as irresistible as the forward movement of 

 time itself. 



We have done our feeble endeavour to briefly sketch 

 the formation of lakes upon the upper courses of river 

 systems, and to show how they form natural reservoirs 

 for the water, which in the end overflows the basin, 

 and (except in those very rare instances, such as the 

 Dead Sea, and the Caspian Sea, where the inflow is 

 balanced by evaporation) finally makes its exit to 

 the sea. 



These operations, as we believe, form the groundwork 

 upon which every great river system is built up the 

 original form of the river course having probably been 

 in most cases a chain of lakes standing at different 

 levels and joined by streams. As time goes on, the 

 second stage in the process follows: the current has 

 now cut through the obstructions, and when that is 

 accomplished, the lake above is emptied, leaving a flat 

 alluvial plain in its place, with a river meandering 

 through its former bed until the water passes out through 

 the more or less deep gorge which has been cut through 

 the divide; where this has been worn through rock, a 

 gorge with more or less perpendicular sides probably 



