Large, semi-permanent areas of ice that become dense due to weight and gravity, and flow toward lower elevations until they melt or enter the sea.
Large, semi-permanent areas of ice, typically found at altitude or in areas closer to the poles, that become very dense under the weight of additional snowfall every year. They eventually gain enough mass to flow under their own weight toward lower elevations, until they reach areas warm enough for adequate melting and enter streams or rivers, such as in most mountain ranges, or melt or break up into the sea, such as in Greenland and Antarctica. Some are accessible enough to be easily visited by tourists.
