It is true that waterfalls develop from the erosion of rivers and rivers often originate from glaciers, but this may not always be the case
A waterfall may also form across a fault, or crack in the Earth's surface. An earthquake, landslide, glacier, or volcano may also disrupt stream beds and help create waterfalls. Hence, we can see that waterfalls usually originate from the flow of rivers and other water bodies. The source of rivers need not always be glaciers. Rivers often get their water from many tributaries or smaller streams that join together. Many rivers, including the Rhone in Western Europe, begin as streams in mountains or hills. As ice and snow melt, streams begin to flow downward from high mountains and the bases of glaciers. When a glacier is a river's source, the river has glacial headwaters. The Ganges River has glacial headwaters. The source of the Ganges, in India and Bangladesh, is the Gangotri Glacier in the Himalayas of northern India. Other sources of rivers can also be springs and lakes.