♪ some of the most picturesque landscapes on earth owe their existence to glaciers. there are many examples-- spectacular mountain ranges such as the alps, the himalayas, and the rockies were sculpted by repeated glaciation. yosemite valley, here in the sierra nevada mountains, would have been another nondescript river valley if glaciers hadn't carved it to its present shape. many of the world's most beautiful lakes were gouged out of hard rock by glaciers, including north america's great lakes and the famous lochs of scotland. even the great expanses of rich agricultural soils that blanket china and the soviet union, canada and the united states owe their existence to glaciers. moving glacial ice pulverizes the underlying rock into silt-sized fragments. this silt was eventually transported and concentrated by the wind into the vast fertile soils of today. early scientists didn't really appreciate the important geological role of glaciers. even geologists were convinced that...