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.
HD Radio uses the same spectrum now occupied by the standard AM and FM bands. The same stations broadcast the digital component simultaneously with the analog signals. The AM spectrum extends from 535 to 1705 kHz, and FM ranges from 88 to 108 MHz.