Glaciers advanced from Canada and retreated four or more times. Over a few million years, Puget Sound was carved and scoured by glaciers. Heavy Pressure. Glaciers containing up to 2,383 cubic miles of ice pushed over the Puget lowland.
AM stands for amplitude modulation, while FM stands for frequency modulation. In AM, the amplitude (the height or depth of the crests or troughs) changes, while in FM, the fre â¦ quency changes. Answered.
A.M. radio uses amplitude modulation. F.M. radio uses frequency modulation. There is no difference with respect to the energy of the signal. The difference in the radio in your car is that waves relying on amplitude get cut off by big structures like bridges.