THE ICE AGE. 93 



tity of both, and legitimately conclude that the agency in each case 

 was the same. 



And let us select the Alps, as the first field for our explorations, 

 renowned for the phalanx of illustrious minds who have studied this 

 subject there, and famous as embracing those districts where the pres- 

 ence of traveled blocks first aroused inquiry, and their significance 

 gave birth to the theory we are testing. 



. The Alps cover with their various arms, encircling ranges and sub- 

 ordinate elevations, all Switzerland ; her lakes are nestled within their 

 valleys, her rivers spring from their frigid slopes, her cities rest upon 

 the debris of their attrition, while the strange and romantic loveliness 

 which surrounds their fields of ice cover it as with a garment of im- 

 perishable beauty. The Alps are the result of gigantic upheavals, 

 probably conducted through ages, which succeeded each other through- 

 out the Tertiary age, and were continental in their extent. The Pyre- 

 nees, the Julian Alps, the Balkans, the Apennines, and Corsica, were ele- 

 vated in this series of vast perturbations, a long range of towering moun- 

 tains whose influence upon physical and social development has been as 

 marked as the revolution it signalized in the world's topography. Eu- 

 rope, which had worn the flora of America, then lost it, and the sassa- 

 fras, liriodendron, maple, and magnolia, failing to survive the climatic 

 changes which intervened, yielded before the gradual growth of dis- 

 tinctively European species. 



The Alps, after passing up along the eastern boundary of Piedmont, 

 irregularly in long, deep bends and winding arches, run east and west, 

 gathering upon their flanks innumerable lesser ranges, and knots of 

 mountains, or in places subdividing into new and splendid lines of 

 peaks which, diverging to the north, afterward unite with the parent 

 chain or melt into the plain of Germany, through successive stejDS. A 

 great congeries of intermingling and twisting ranges communicates the 

 original disturbance over Switzerland, and the radiate lines of agitation 

 may be traced southward upon the plains of Piedmont, through the 

 Apennines into Italy, and by the Illyrian Alps into Dalmatia. The 

 Alps inclose valleys and plateaus ; their highest summits are scored by 

 deep gulches which descend their sides ; and broad crevices, ravines, 

 and passes, ramify along their slopes. Into these troughs, far above 

 the snow-line, fed by confluent furrows, the snows of winter have col- 

 lected, and heaped up layer upon layer accumulated to great depths. 

 The water of the melted surface percolating through these subjacent 

 films, an increasing pressure has solidified them to a semi-icy state. 

 Slowly in these deep fields of snow, by pressure, by alternate thawing 

 and melting, the molecular condition of the mass undergoes a change, 

 and becomes compacted into crystalline ice. Before this change is 

 consummated, the mass of snow, ice, and congealing water, is called 

 the oi^ve. Thus formed, there emerge from these upper reservoirs vast 

 sheets of ice which pass down between clifl's and crags, winding oyer 



