The Rocky Mountains are described as younger because the Rocky's are really two mountain chains. The older mountain chain started billions of years ago, and the younger mountain chain pushed the older mountain chain up more, only 60 millions years ago.
Contagious diffusion is wide-spread and involves interpersonal contact.
Answer:
One way that glaciers change the landscape is by erosion. As they pass over the ground, the ice scrapes up soil and rock. A valley glacier will leave a valley much deeper, as it erodes the underlying surface with plucking and abrasion.
C IT DEPENDS ON A VARIETY OF FACTORS
