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If the shortest distance between two points is a straight line, why do rivers meander their way towards a larger body of water? Today, we answer this question with help from MinuteEarth.
In states like Nevada, Washington and Vermont, a river’s course is determined by the mountainous structures surrounding it. Like MinuteEarth mentions, these rivers “are literally set it stone.” But, in states like Indiana and the Great Plains, river banks made of soft soil can easily shift and change a river’s course.
According to MinuteEarth, all it takes is a little disturbance and a lot of time. It's a good thing nature has plenty of both.
If one bank of a river is disturbed and begins to crumble, water fills the hole and sweeps away loose dirt. Over time, this creates a bigger and bigger hole in the river bank. As the water begins to rush faster through the new opening, it slows on the opposite river bank. Because slow-moving water can’t carry as much weight as fast-moving water, loose dirt and rocks build up on that side, making it more shallow. Eventually, the build-up creates new land and a new curve in the river’s watercourse.
The new curve causes the water running against the outside bank to pick up enough momentum that it slams into the opposite bank further down the river, creating another curve. As more time passes, the rushing water creates more and more curves downstream.
Even though the wider the river, the longer the distance is to the next curve, MinuteEarth explains that the creation of these curves tends to happen in a similar pattern all over the world. Generally speaking, the length of one S-shaped curve is about six times the width of the river.
And, as long as nothing interferes, this process and pattern will continue, and the river will grow curvier and curvier.
Looking for more Never Stop Asking "Why?" questions? Catch up on all of the past "Whys" on the blog!
