Most of the Earth is water, about 97 percent of it in the ocean. Clouds carry water droplets inland by weather systems, and when the water droplets become too big, they fall as rain, hail, or snow, depending on the temperature. This is when water meets land, waters it, erodes it. As water fall on streams, it flows into rivers which then cut into the rocks on the riverbed and land on either side. Over eons of time, this process of erosion can create spectacular effects. A famous example: in the US, the Colorado River has sliced down through rocks representing two billion years of Earth’s history, forming the Grand Canyon in Arizona.
One of the most intriguing and perhaps, slightly bizarre landforms to be found in a canyon is the ‘hoodoo.’ It is formed because different rock types erode at different rates. Dolomite, limestone and siltstone, for example, are hard, while mudstone is soft. One of the best places in the world to see hoodoos is Bryce Canyon National Park in Utah.
On their way to the sea, rivers not only cut through the rocks to form valleys, canyons and gorges, but also erode the bedrock on the riverbed to create waterfalls. Here, the river tumbles over a vertical drop of a series of drops, and the result can be sensational as can be seen in Angels Fall in Venezuela, the Ruacana Falls in Namibia, or the Gullfoss and Dettifoss in Iceland. The last two are ‘multi-step’ waterfalls in which there is a series of falls of roughly the same size, each with its own plunge pool.
Eventually, all that water is returned to the sea, completing the water cycle. Indeed, some waterfalls plunge directly into the sea. Back into the ocean, water turns back on itself and attacks the land as when waves slam into cliffs or when rock fragments are picked up by the waves and thrown against them, causing them to collapse.
Tumultuous seas swept by fierce winds can reshape rocks into sea stacks, some of which are towering pillars that seem to rise mysteriously from the deep. On Foula, the most westerly island in the remote Shetland in the north of mainland Scotland, wave action has resulted in the formation of spectacular sea stacks standing where softer rocks in a promontory have been eroded, leaving behind the harder rock.
Leonardo da Vinci’s famous quote that “with time and water, everything changes” is an apt description of the power of natural water as a agent of change, as we saw in the above description and as you will see in the images below.