The size of an alluvial fan seems to be related to many factors, such as the physiography and geology of the source area and the regional climate. There appears to be no lower limit to the size of fans as the feature may appear on a microscale in almost any environment. It is known from studies in various parts of the world that a large number of modern-day fans have a radius from 1.5 to 10 kilometres. Some fans have a radius as large as 20 kilometres, but these are rare because fans of that size tend to merge with ...(100 of 32811 words)