Water – whether liquid or as ice – Is the great shaper of our planet. From the highest mountains to the great plains, flatlands, cliffs in the coastline or in sandy beaches, water is the main agent of erosion, transport and sedimentation. Even in the driest deserts, the features are everywhere of the action of past or present water.
The Arches National Park
The Arches National Park in the U.S. State of Utah is located between 1,300 and 1,700 metres above sea level on a rocky arid desert with temperature fluctuations of up to 50° C. The formation of the arches has a long history that began three hundred million years ago. The sea invaded the area repeatedly, then each time evaporated, so amassing huge amounts of salt, which were covered by newer sandstones, which today form the arches.
With their granite walls standing hundreds of feet almost vertically above a calm blue sea, the Fjords are one of the greatest spectacles of nature and are a striking reminder of the erosive capacity of the glacial ice that covered these valleys only thirteen thousand years ago, a trifle on the geological scale.
Karst in Guilin, Guaqxi. China
The Karst are landscapes created by the underground dissolution of limestone. In these areas, water seeping through cracks in the rock dissolved and created large caves and underground cavities that, when collapsing, generated circular surface depressions and a characteristic landscape.
In some places the soil layers are formed of limestone and dolomite, very similar to limestone but with a lightweight magnesium content which makes it less soluble. So while the limestone is dissolved, the masses of dolomite resist and form residual dome-shaped profiles. In the Guilin scenery, this type of erosion has finally generated one of the most beautiful and representative landscapes of China.
Possibly the most famous river canyon on Earth, the Grand Canyon stretches for about 350 km and presents cliffs nearly 2,500 metres high. But the highlight of the Grand Canyon is that this huge river cut through fluvial sedimentary strata that now tell the history of the planet over a period from 2,000 million years ago until about 230 million years ago .
The formation of the canyon itself began about 6 million years ago with the development of the Colorado River, and was accelerated during the last two million years when, during glaciations, the river and the strength of its erosive flow increased.
The Hoover Dam, once the largest concrete structure ever built, was erected below the Grand Canyon in the 1930s, and allowed the regulation and use of the Colorado River. Due to its gigantic scale it soon became one of the earliest evidences of environmental problems that this kind of works can create – such as the drastic recession of the coastal area of the Colorado delta-.
Giant Boulder of Tongatapu
On the small island of Tongatapu, about two thousand kilometres north of New Zealand in the South Pacific, a coral block about nine metres high and nearly fifty in perimeter, which is 130 metres from the coast and about 15 metres above sea level, is the largest known stone block moved inland by a tsunami. Geologists estimate that this gigantic coral block weighs about 1,600 tons and believe that the time of its deposit is no longer ago than 7,000 years.
While this is certainly the largest of the giant blocks left by the huge wave that swept the island in the past, other blocks the size of houses or buses located about 10 or 20 metres above sea level, can be found in the fields of Tongatapu. Currently submarine volcanoes in the area appear to be .::
It is considered the largest delta on the planet and possibly the largest example of fluvial building on Earth . In this region, with unique features, a huge population is settled on the fertile delta lands, where they find food, but where they have to put up with periodic natural flooding and other – sometimes less obvious – environmental risks to their lives in such a place.
One of these risks, also related to water, is due to groundwater springs being contaminated by arsenic. The problem originated in the seventies of the last century, when development aid funded the construction of wells to supply water to the population who hitherto drank untreated surface water, which caused severe epidemics. However, the new wells drained deep water that naturally had high levels of arsenic, thus poisoning the population and creating one of the world's most serious public health problems associated with the quality of water.
Supracrustal rocks of Issua. Greenland
In remote Greenland, at the edge of the Greenland ice cap, about one hundred kilometres northeast of the small town of Nuuk – the administrative capital of this vast territory – about 3,750 million years ago some old rocks were formed under shallow waters by sedimentation of lava and the debris of marine erosion.
These rocks are the earliest evidence of liquid water on our Planet, and were formed eight hundred million years after the accretion of the meteoritic material that originated the Earth
Giant Ripples of Altai. Siberia
Ripples are small wavelike forms made by currents in sediment under certain conditions. Most common measurement is of ripples of a few centimetres in height, and it is very easy to see such forms on the sandy shores of beaches, lakes and rivers.
However, in the Kurai basin in Russia, the ripples are up to 20 metres high and a hundred from crest to crest. Their origin is related to catastrophic floods due to the violent drainage of large glacial lakes. Some glaciers and ice caps naturally dam up huge lakes that, when glaciers melt, can overwhelm and even collapse them, so generating water flows that devastate everything in their path and creating these giant features in the terrain.
Great Blue Hole. Belize
This sinkhole is unique as it is situated under the ocean and a small atoll has formed around it.
Sinkholes are circular depressions caused by the collapse of the ground over a cave excavated by dissolving limestone. As this process takes place on dry land, it means that this particular sinkhole was formed during the last glacial period, when the ocean waters were 120 metres below the present level.
Saidmareh Landslide. Zagros. Irán
These are landslides which occurred due to gravity, but in which water plays a decisive role as it overloads and destabilises the ground and lubricates the movement of soils and rocks. The immediate cause may have been heavy rains that soaked the ground, or an earthquake that destabilised it, but once a mass of land is set in motion it can trigger a domino effect, increasing its volume to move millions of cubic metres.
The largest known landslide occurred in the Zagros Mountains about ten thousand years ago, and mobilised some 20 kilometres of earth and rock over fourteen kilometres, covering an area of about 50 square kilometres, diverting rivers and creating new.