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.
am radio ranges from 535 to 1705khz kilohertz or thousands of cycles per second of electromagnetic energy these are the numbers you see on your am radio dial n ote in the tan area at the left of the illustration below that am radio waves are of a lower frequency than either fm radio or tv waves or the most part fm and tv signals are line of sight although this means that fm stations don t interfere with each other this characteristic creates a couple of other problems first these waves go in a straight line and don t bend around the earth as am ground waves do