<P> A river sometimes flows over a large step in the rocks that may have been formed by a fault line . Waterfalls can occur along the edge of a glacial trough , where a stream or river flowing into a glacier continues to flow into a valley after the glacier has receded or melted . The large waterfalls in Yosemite Valley are examples of this phenomenon , which is referred to as a hanging valley . Another reason hanging valleys may form is where two rivers join and one is flowing faster than the other . Waterfalls can be grouped into ten broad classes based on the average volume of water present on the fall ( which depends on both the waterfall 's average flow and its height ) using a logarithmic scale . Class 10 waterfalls include Niagara Falls , Paulo Afonso Falls and Khone Falls . </P>
<P> A river sometimes flows over a large step in the rocks that may have been formed by a fault line . Waterfalls can occur along the edge of a glacial trough , where a stream or river flowing into a glacier continues to flow into a valley after the glacier has receded or melted . The large waterfalls in Yosemite Valley are examples of this phenomenon , which is referred to as a hanging valley . Another reason hanging valleys may form is where two rivers join and one is flowing faster than the other . Waterfalls can be grouped into ten broad classes based on the average volume of water present on the fall ( which depends on both the waterfall 's average flow and its height ) using a logarithmic scale . Class 10 waterfalls include Niagara Falls , Paulo Afonso Falls and Khone Falls . </P>
where does the water come from for yosemite falls
where does the water come from for yosemite falls
a stream or river flowing into a glacier continues to flow into a valley after the glacier has receded or melted
a stream or river flowing into a glacier continues to flow into a valley after the glacier has receded or melted