A river may begin as a trickle of melting snow, high on a mountaintop. It may begin as a trickle of underground water, bubbling out from under a rock on a mountainside.
The trickle winds down the mountainside, following the easiest path in and out among the rocks. It is so narrow you could step across it. Farther down the mountainside, it is joined by another little trickle. The two of them move along together, forming a wider, faster-moving stream,
Soil and stones, carried along by the rushing water day after day, year after year, cut a groove into the mountainside. The bottom of this groove is the bed of the stream. And the high sides of the groove are its banks.
One after another, more trickles join the stream and it grows wider. Now it is a river, fast and wide, rushing down the sloping mountainside.
In one very steep place, the fast-moving rivers has worn away the soft rock. Only bumps of hard rock are left. These rocks stick up out of the riverbed. The river swirls and foams around them. This part of the river is called the rapids.
Not far from the rapids, the mountainside ends in a cliff. The rushing river hurries to the edge of the cliff and falls hundreds of feet (meters) in a roaring, tumbling, splashing, waterfall.
The bottom of the waterfall is near the bottom of the mountain. The land there slopes very gently, so the river moves more slowly. The river leaves the mountain behind and flows out onto a plain. There, it moves even more slowly, because the plain is almost level.
Other rivers from other mountains join the first river. Together they become a great, broad river that flows slowly across the plain on its jouney to the distant sea
The trickle winds down the mountainside, following the easiest path in and out among the rocks. It is so narrow you could step across it. Farther down the mountainside, it is joined by another little trickle. The two of them move along together, forming a wider, faster-moving stream,
Soil and stones, carried along by the rushing water day after day, year after year, cut a groove into the mountainside. The bottom of this groove is the bed of the stream. And the high sides of the groove are its banks.
One after another, more trickles join the stream and it grows wider. Now it is a river, fast and wide, rushing down the sloping mountainside.
In one very steep place, the fast-moving rivers has worn away the soft rock. Only bumps of hard rock are left. These rocks stick up out of the riverbed. The river swirls and foams around them. This part of the river is called the rapids.
Not far from the rapids, the mountainside ends in a cliff. The rushing river hurries to the edge of the cliff and falls hundreds of feet (meters) in a roaring, tumbling, splashing, waterfall.
The bottom of the waterfall is near the bottom of the mountain. The land there slopes very gently, so the river moves more slowly. The river leaves the mountain behind and flows out onto a plain. There, it moves even more slowly, because the plain is almost level.
Other rivers from other mountains join the first river. Together they become a great, broad river that flows slowly across the plain on its jouney to the distant sea
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