Waterfalls can flow spontaneously

The breathtaking waters that cascade from steep cliffs can be productions made by yourself.

It has long been thought that waterfalls needed an external force to form – like an earthquake, a landslide or a change in sea level – which molds the rocky edges, the water tumbles.

But a new study suggests that a waterfall can form without any external influence. The chaotic nature of a river can shape the bedrock and spontaneously create a waterfall, researchers said yesterday (March 13) in the journal Nature.

To demonstrate this, the group of researchers first created a river model in a laboratory. [Gallery: Most Famous Waterfalls in the US]

They used a material called polyurethane foam to model the natural bedrock formed by the cascades. This material is scalable and adapts to rocks but erodes much faster. The foam was placed at an incline of 20 degrees down in a channel 24 feet long (7.3 meters).

Then the researchers opened the "stream", releasing sediment-laden water into the canal.

They found that under the pressure of water and sediment, the layer of "rock", once rectilinear, began to erode unevenly and become wavy. Some parts of the bedrock have not eroded at all, creating ridges, while others are eroding strongly, creating steep hills. In other words, the bedrock began to look like a series of steps.

In a little over 2 hours, water began to flow on the less eroded ridges and to sink into the most eroded pockets; the scientists had their stunts. These laboratory-made cascades lasted about 20 minutes before the ridges were completely eroded. The researchers calculated that the life span of their laboratory-made waterfall was 10 to 10,000 years of the life of a natural river, according to the study.

The authors concluded that some (but not all) natural waterfalls could occur spontaneously, similar to those made in the laboratory. If they can determine which cascades have formed spontaneously and which ones have been helped, this could help to better understand how our landscapes throughout the history of our planet.

Originally published on Science live.