The largest collapses in history. NASA will begin tracking landslides around the world

The largest known landslide is located in the Heart Mountains in Wyoming (USA). It covers an area of ​​two thousand square kilometers and, judging by the remaining traces, in some places it spread at a speed of one hundred kilometers per hour. This catastrophe happened in the very distant past - about thirty million years ago.

In Europe, the first place belongs to the Flim landslide, which occurred in the Alps. Scientists suggest that it occurred before the Ice Age and before the appearance of humans here (about a million years ago).

Twelve cubic kilometers of loose material moved into the Rhine River valley. This happened on the territory of what is now Switzerland near the city of Chur - where the village of Flim (canton of Grisons) is now located. The landslide fell into the Rhine, and the river valley was buried to a height of about six hundred meters. At first a lake two hundred meters deep formed, but it did not last long. The Rhine found another way, and the lake was drained.

And the largest landslide of historical time is considered to be the event that occurred on February 18, 1911 in the Pamirs. The landslide was caused by a strong earthquake, after which a fantastic amount of loose material—2.2 billion cubic meters—slipped from the slopes of the Muzkol ridge, from a height of five thousand meters above sea level. The village of Usoy with all its inhabitants, their property and livestock was overwhelmed. Rock formations blocked the valley of the Mugrab River. A huge dam with a diameter of four to five kilometers and a height of more than seven hundred meters stopped the flow of the river for four years. A new lake in the Pamirs appeared - Sarez, which began to grow rapidly and in turn flooded the villages of Sarez, Nisor-Dasht and Irkht.

In 1913, the length of Lake Sarez reached 28 kilometers, and its depth was almost 130 meters. Then the waters of Mugrab made their way through the stone blockage, but the lake still continued to grow. Today its length is already 75 kilometers, and its depth is about five hundred meters.

The force of the impact of the mass of earth and stones falling from a great height was so great that it generated a powerful seismic wave. It was recorded by seismic stations around the world as it circled the globe several times.

The mystery of the Usoi landslide is its exceptionally large size. Until now, scientists cannot say for sure whether there has ever been a similar landslide on the globe (in historical times). Traces of a more gigantic one have not yet been found.

The roar of collapsing rocks (some scientists attribute this landslide to landslides) was heard by residents of Tajik villages located twenty kilometers from the village of Usoy. People called this place “Death Valley” and walked around it for a long time.

And the most tragic in terms of the number of victims was a landslide that occurred in the Chinese province of Gansu in 1920. Most of the territory of this province is occupied by a loess plateau, which suffered a terrible earthquake. Not only the strength of the earthquake, but also the specific soil conditions of Central China played a fatal role here. The affected area was in the center of the “land of loess” - fertile dust blown by winds from the Gobi Desert at the beginning of the Quaternary period. The fertility of the soil was the main reason that this area was densely populated.

Loess is very porous, but at the same time it has quite significant strength. Therefore, canyons and valleys with steep slopes are formed in loess areas. When the cohesion of the loess was disrupted by the earthquake, the slopes became unstable. Loess strata moved literally in entire hills. These hills buried tens of thousands of people who lived in caves dug in the loess. In one cave lived the Muslim prophet Ma the Blessed with his community of three hundred of his followers. They were cut off from the whole world and doomed to a slow and painful death. For a whole month afterwards, relatives and fellow believers of the victims dug up the loess cover that closed over their cave, but they could not find anything.

The tragedy was made even worse by the fact that it happened on a winter night. The ensuing darkness and cold forced almost the entire population to take refuge in their homes. At 7.30 pm a dull noise was heard from the north, “as if huge, heavily loaded vehicles were rushing at breakneck speed along the bad pavement.”

One missionary, who miraculously survived, later said:

“When I heard the noise, I thought it was an earthquake and ran outside. But as soon as I found myself on the street, I felt as if something had hit me in the back with terrible force.

With my legs spread wide, like a drunkard trying to stay on his feet, I felt a strong rotational movement of the earth beneath me...

This first and longest shock lasted two minutes. He was followed by five or six others, and so quickly that it was almost impossible to separate them from one another...

The shocks followed one after another with an interval of several seconds and merged with the deafening roar of collapsing houses, the screams of people and the roar of animals that came from under the rubble of buildings.”

The resulting landslides reached enormous proportions. The seven most gigantic of them cut off the slopes of the mountains, and thousands of cubic meters of loess filled up the valleys and covered cities and villages. One of the houses, captured by loess, was carried on a moving mass of rocks and simply miraculously remained on the surface. There was a man and a child in this house, but in the pitch darkness and deafening noise they didn’t even really understand what had happened. In the morning, a truly apocalyptic picture opened before them - “the mountains moved,” and they did not even recognize their native places.

The section of road that moved along with their house (about four hundred meters long) moved down one and a half kilometers. Having stopped, it subsequently almost retained its former appearance, and the tall poplars on both sides of the road continued, as before, to sway their branches. The house made a path of almost one kilometer, and then two other landslides caused the avalanche to change direction.

This place is also called “Death Valley” because 200,000 people were buried here.

In our country, landslides occur very often in the Nizhny Novgorod region. This was even reported in ancient chronicles. For example, in the 15th century, a landslide descended from Gremyachaya Mountain, which destroyed a large settlement. This is how this event is recorded in the chronicle: “And by God’s will, sin for our sakes, the mountain crawled from above the settlement, and one hundred and fifty households with people and all kinds of livestock fell asleep in the settlement.”

A large landslide also occurred on the night of June 17, 1839, near the village of Fedorovka on the left bank of the Volga between Saratov and Ulyanovsk. The earth moved underfoot, houses cracked and shook, and there was noise and roar in the air.

Nobody understood what happened. People did not know where to run and how to save their lives. Women and children screamed and cried loudly. Dawn came, but it did not bring peace - everything around remained the same, and the earth even began to shake even more. In places it swelled, and in place of lowlands, hills grew, and in place of hills, gaps and cracks gaped.

The vibrations of the earth's surface (sometimes strong, sometimes weak) lasted for three whole days. And all this time the population was in constant anxiety and excitement. And when everything calmed down, it turned out (to the great amazement of the residents!) that the village of Fedorovka had “moved” closer to the Volga by several tens of meters.

Landslides most often occur when the underlying bedrock, composed of limestone or other carbonate rock, is eaten away by acidic groundwater, subsides after heavy rainfall, or is damaged by pipe ruptures. Such sudden collapses are especially dangerous, for obvious reasons, in cities, where entire houses can suddenly go underground. Below you will find photographs from the sites of the largest landslides in recent decades:

In May 1981, this giant hole appeared within the city of Winter Park (Florida). Local authorities decided to strengthen the edges and turn the resulting hole into a picturesque city lake.

In 1995, two houses in a fashionable area of ​​San Francisco fell into this hole (18 m deep, 60 m long and 45 m wide).

In 1998, after unusually heavy rainfall and a sewer pipe ruptured in San Diego, a giant crack appeared. Its length is about 250 meters, width – 12 meters and depth – more than 20 meters.

In 2003, rescuers had to pull out this bus with a crane after it suddenly fell into the ground on a street in Lisbon (Portugal).

This hole swallowed up several houses in the capital of Guatemala in February 2007. Three people are missing.

Bird's eye view.

In March 2007, in the Italian city of Gallipoli, a road collapsed into a network of underground caves underneath.

In September 2008, a car driving along one of the streets in the Chinese province of Guangdong suddenly found itself in a hole 5 meters deep and 15 meters wide.

This giant crater was formed in May 2010 in Guatemala City after Tropical Storm Agatha swept through it.

The same funnel from a closer distance.

In May 2012, as a result of a soil collapse on the roadway in the Chinese province of Shaanxi, this hole appeared 15 meters long, 10 meters wide and 6 meters deep.

And another landslide in Shaanxi (6 meters deep and 10 meters wide) damaged three gas pipes and one water pipe in December 2012.

This giant hole formed one December night in 2012 in southern Poland. Its depth is about 10 meters, width is about 50 meters.

In January 2013, part of a rice field in the Chinese province of Hainan fell into the ground. Over the previous four months, there were about 20 similar incidents in the district.

The most catastrophic collapses in America

A selection of photographs from the sites of the largest landslides in recent decades in America.




Unlike landslides, landslides originate from less steep slopes. Their movement occurs smoothly, calmly over hours, days and even months.

River water that has seeped deep into the earth's crust has a treacherous effect. It impregnates layers of loose sediments and moisturizes clays. Often such a moistened layer plays the role of a lubricant between the layers of the earth, and the upper layer, as if on a sled, begins to slide and float down. Small landslides are called “slides”.

MAXIMUM NUMBER OF LANDSLADE VICTIMS

On December 16, 1920, an earthquake caused a landslide on a mountain in Gansu Province (China), killing 180 thousand people.

MAJOR LANDSLADES IN RECENT YEARS

Several hundred people died on March 29, 1994, when persistent rains near the city of Cuenca in Ecuador caused a landslide that buried a mining village.

In June 1997, two landslides in gold mines in the Chinese province of Yanan killed 227 miners.

In September 2002, in the Karmadon Gorge (North Ossetia), more than a hundred people died, including the film crew of S. Bodrov Jr., as a result of the collapse of a huge glacier and landslide.

LANDSCAPE THAT SWALLOWED A CITY

The town of Saint-Jean-Vianny in the Canadian province of Quebec was completely abandoned after a landslide in May 1971. The city was built in the 17th century by the first settlers - in a secluded depression on the edge of a giant slope. Its inhabitants lived without any natural disasters for several hundred years. And on May 4, 1971, the first sign of an impending threat followed, when livestock refused to go out into the fields on the edge of the city: most likely, the animals felt minor vibrations in the soil. That same night, a huge landslide occurred. Roads, vehicles and houses were swallowed up by a huge wave of mud 15 meters high, which spread over 15 kilometers within three hours. As a result, 31 people died, and the city is still empty due to strong movements of the layers of clay lying underneath.

THE BIGGEST LANDSLAND IN ITALY'S HISTORY

The Piave River Valley is located in northern Italy and thanks to E. Hemingway’s novel “A Farewell to Arms!” familiar to millions of people. During the First World War, the Italian army was stationed here, operating against the Austrians after their defeat at Caporetto. On October 9, 1963, at 23.15, a terrible natural disaster occurred - the entire valley of the Piave River was flooded. There were reports that the 260-metre Valmot Dam had collapsed under the pressure of a massive landslide caused by the earthquake.

The world's tallest dam, more than 20 meters thick, withstood the earthquake. It collapsed a little later. As the surviving witnesses of the disaster recall, the roar that was heard before the huge water shaft collapsed into the valley had a different origin. It came from the mountains that had cracked on either side of the dam. There is testimony from Captain Fred Mickelson, the pilot of the US military helicopter that evacuated the residents of the village of Casso. The village stood above a dam and was in danger of residual landslides. He described the event as follows: “Behind the dam there was a lake about two kilometers long, but now it is no longer there. The tops of the rocks on both sides of the dam fell into the lake and literally filled it.”

The water forced out of the lake poured through the dam, destroying it, and with a giant waterfall 450 meters high at right angles it poured into the valley of the Piave River.

Longaron, a village located in the path of the water flow, disappeared instantly. 3,700 of the 4,000 inhabitants died. In Pigaro, only the bell tower, the cemetery chapel and one house survived. Until now, no one lives in the village.

THE WORST LANDSIDE IN EUROPE

For centuries, mountains of waste rock grew in the vicinity of mining towns such as Aberfan, in Wales (England), being an integral attribute of the mines. Due to their composition, such mountains are very unstable and mobile. In Aberfan, a stream flowed under the mountain, which, washing away the base, further reduced its stability. A few days before the disaster, local residents noticed some movement on the mountain and notified authorities.

On the morning of October 21, 1966, a representative of the municipal government climbed the mountain to check the information received. While he was inspecting the mountain, suddenly two million tons of rock began to move and fell on the city. The roar was heard several kilometers from the town. Rescue work began immediately, the miners rose to the surface and, together with the townspeople, began excavations. 43 people died - mostly children who were at school at the time.

LANDSlide, separation and sliding movement of a mass of rock down a slope; the sheer mass of displaced rock. O. are common in areas where weak plastic and impermeable rocks are covered by relatively strong permeable ones. The weakening of the strength of rocks is caused by natural causes (increasing the steepness of the slope, washing away its bases by waves and as a result of river erosion, waterlogging of soils with melt and rainwater, infiltration pressure in the rock mass caused by fluctuations in sea level, reservoir or river water, seismic tremors, etc. ) or human intervention (destruction of slopes by mountain and road excavations, excessive grazing or watering, deforestation, improper agricultural practices of slope agricultural lands, construction load on the edge or upper part of the slope, etc.). The emergence and activation of water is facilitated by the technogenic rise in groundwater levels on the banks of reservoirs. O. shift along the slope by several meters, often by tens and hundreds of meters. The volume of displaced rocks ranges from several tens of m3 to 1 billion m3. Large lakes form on steep slopes. 15° at a distance from watersheds, often occur on the sides of valleys, high shores of seas, lakes and reservoirs. They retain a certain coherence and solidity inside the landslide body, the thickness reaches 10–20 m or more. Small lakes transform the sides of ravines everywhere. Often O. are located on a slope in several tiers (for example, in the valley of the Moscow River).

In plan, landslides often have the shape of a crescent, forming a depression in the slope (the so-called landslide circus). Shallow cirque-shaped dents on the steep slopes of valleys and ravines - osovy - appear as a result of surface displacements of highly moistened loamy masses, especially with the slow melting of snow on shady slopes. After the rock is torn off and disappears, a bare surface or niche remains on a steep slope—a landslide ledge. Landslide breccia accumulates at the foot of the slope. A pressure landslide shaft may appear in front of the moving lake front. The tongue of the lake often extends into the waters of a watercourse or reservoir, changing the configuration of the coastline. The basis of the slide is the base of the slope or a separate flattened section of the slope, where the movement of landslide masses stops. Free sliding of a landslide body occurs if the shifting blocks are developed above the base of the slide; in the case when the thickness of plastic rocks lies below, these rocks are squeezed out, accompanied by their movement against the general slope (O. squeezing out I). Rocks that have not lost the natural composition of rocks in their blocks are classified as structural rocks. In “cutting” rocks, the sliding surface cuts off different layers of rocks. When fine particles of fine earth are washed out from the base of the lake by spring waters, weakening the stability of the overlying rocks, it is classified as a type suffosion O. (widely distributed on slopes with a steepness of 10–18°). Possible landslides-flows with a fluid consistency of soil, their volume can reach millions of m3. Small surface water-saturated lakes—slides (width up to several meters, depth from 0.3 to 1.5 m) are formed under conditions of excessive moisture to a plastic (mud-like) or fluid state.

Slopes susceptible to landslide processes are characterized by pseudo-terraces (often with a reverse slope), mounds, swampy closed or poorly drained semi-closed depressions and other forms of landslide relief, as well as a specific appearance of vegetation (for example, the so-called drunken forest). In O.'s body, rupture cracks are observed. In the European part of Russia, lakes are distributed along the sides of the valleys of large rivers (especially the Volga and its tributaries), reservoirs, and along the Black Sea coast. The coasts of the Black Sea are marked by powerful landslide activity - in Crimea, near Odessa (Ukraine) and in Adjara (Georgia). A wide strip of water stretches for hundreds of kilometers along the coasts of the Mangyshlak Peninsula (Kazakhstan). Landslide danger is observed in most mountainous countries (the eastern periphery of Tibet, the Himalayas, etc.). Lakes that come down from the sides of mountain valleys often form temporary dams that dam the river, forming a landslide lake. The catastrophic consequences of the flood wave that occurs when such a dam is destroyed many times exceed the negative consequences of the displacement of the reservoir itself. Great damage to the reservoir is caused to agriculture. lands, industrial enterprises, populated areas, etc. To combat them, bank protection and drainage work, forest planting, and securing slopes with piles are carried out.

On relatively steeply inclined areas of the bottom of oceans, seas, and deep lakes in seismically and volcanically active zones, as well as on the frontal slopes of underwater deltas (as a result of sharp differences in sedimentation rates), underwater oceans are found; one of the largest is the Sturegga landslide in the Norwegian Sea (length approximately 800 km, width 290 km). Underwater oxygen can cause the rupture of submarine cables, which has happened repeatedly, in particular, at the bottom of the Atlantic Ocean.

Table. Catastrophic landslides*

Location (current geographic location indicated)

Event characteristics

Volume of solid waste, m3

Devastating consequences and loss of life

980 BC e.

No data

Destruction. Death of "an enormous number of people"

373–372 BC e.

Greece, North coast of the Peloponnese Peninsula

Seismogenic landslide

The disaster led to the immersion of the ancient city of Helios and a kilometer-long stretch of coast into the waters of the Gulf of Corinth

Beginning of the century e.

Iran. River valley Saidmarrekh

The largest landslide from Mount Kabir-Bukh crossed a valley 8 km wide and crossed the high ridge. 450 m

When the river was blocked by a landslide body, a dammed lake 65 km long and up to 180 m deep was formed

Jordan. City of Jarash

Natural-anthropogenic mudflow-landslide disaster

More than 100,000

Burial under landslide masses and mudflow flood b. including the large ancient city of Geras

Russia. City of Nizhny Novgorod

Catastrophic landslide after heavy rainfall

No data

150 households were buried. More than 600 people died.

Seismogenic (?) landslide

No data

The village of Hanko is buried under a landslide mass. 2000 people died.

Russia. South coast of Crimea. Village Opolznevoye

The largest in the South. coast of Crimea in historical time seismogenic Kuchuk-Koi landslide and rock flow

The village was destroyed. A large stream disappeared into the hole. The tongue of the landslide advanced into the Black Sea by 100–160 m

China. Gansu Province. Center. part of the Loess Plateau.

7 seismogenic landslides of large volumes of loess strata, moving entire hills, cutting off mountain slopes

No data

Numerous people were buried. inhabited loess caves, farms and villages. St. died 200 thousand people

Canada. Atlantic. coast

The underwater landslides provoked an underwater turbidity current 330 km wide and (consequence of an earthquake on the Great Bank of Newfoundland at a depth of 800 m)

7 submarine cables were torn and buried at a distance of up to 1000 km from the epicenter. A wave arose that hit the south. shore of the island Newfoundland. Several villages were destroyed. 33 people died.

China. Sichuan Province

Seismogenic landslide of Deihi

Dam break on the river Min. In the city of Deihi, 577 people died.

Japan. Honshu Island, Kobe area

Landslide caused by heavy rains

No data

100,000 houses were destroyed in the city. 600 people died.

Japan. Kyushu Island, Kure City District

No data

2,000 residential buildings were severely damaged or destroyed. 1154 people died.

Cerro Condor-Sencas landslide

A 100-meter dam on the river was destroyed. Rio Montara (followed by flooding)

Tajikistan. The junction of the Zeravshan and Alai ranges

Landslide as a result of the Khait earthquake

On the right bank of the river. Surkhob, the village of Surkhob was buried, the village of Yarkhich was destroyed, nearby villages were destroyed. The villages of Khait and Khisorak were flooded. 7200 people died.

China. Tibet - Himalayas, near the Indian-Chinese border

Numerous seismogenic collapses and landslides of loose rocks saturated with water from monsoon rains

Enormous changes in relief near the epicenter

Japan. Honshu Island. Wakayama Prefecture

The landslide, caused by rainfall that destroyed a series of dams, turned into a mudflow along the river. Arida

No data

1046 people died.

Japan. Honshu Island. Kyoto Prefecture

Minamiyashiro landslide caused by heavy rains

No data

5,122 houses were destroyed. 336 people died.

Russia. Ulyanovsk city

Large landslide on the right bank of the Volga

The drainage gallery is deformed

Japan. Honshu Island. Shizuoka Prefecture

Kanogawa landslide caused by heavy rains

No data

19,754 houses were destroyed or severely damaged. 1094 people died.

USA. Montana

Landslide triggered

Hebjen earthquake

The landslide blocked the river. Madison, creating a dammed lake. 28 people died.

Italy. Province of Belluno. Vayonta Reservoir

As a result of the erosion of the shore, the Vayont landslide quickly descended into the lake

High waves appeared. 260 m and 100 m. Villages in the river valley were destroyed. Piave. The city of Longarone was severely damaged. 3000 people died.

USA. State of Alaska. City of Anchorage

Seismogenic landslides and collapses

The wave generated by the displacement of landslide masses flooded the port facilities. 106 people died.

China. Yunnan Province

Seismogenic (?) landslide

4 villages destroyed. 444 people died.

Great Britain. Wales. City of Aberfan

Technogenic landslide as a result of the collapse of the top of a waste heap

No data

144 people died.

Brazil. City of Rio de Janeiro

A landslide caused by heavy rains, which turned into an earthen avalanche and a mudflow

No data

Approximately died. 1000 people

Brazil. East slopes of the Brazilian plateau. Serra daz Araras

Landslide in the Ribeirão da Floresta valley caused by heavy rains

No data

A section of the highway has been demolished, the road builders' camp has been flooded by the landslide, and that means... part of the nearest village

USA. Virginia

Flooding caused by Hurricane Camille contributed to large landslides

No data

More than 100 people died.

Canada. Quebec. City of Saint-Jean-Viony

Liquefied clay of water-glacial origin flowed along the river valley. Petit Bras at a distance of 2.8 km and disappeared into the river. Seguenay

More than 7 million

The embankment on the river was destroyed. Petit Bras. More than 40 houses were destroyed. 34 people died.

Uzbekistan. Pos. Brichmulla

Technogenically provoked activation of the Mingchukur landslide during the filling of the Charvak reservoir

25–30 million

Partial filling of the reservoir bowl with landslide mass

USA. Western State Virginia. Buffalo Creek Township

The collapse of three coal waste heaps (as a result of heavy rains) caused a landslide that advanced 2–4 km

No data

4000 people were left homeless. 125 people died.

Peru. River valley Mantaro

Giant Mountmark landslide blocks riverbed

The village was destroyed. Mountmarka. A dammed lake 31 km long (depth up to 170 m) was formed. 450 people died.

Abkhazia. River pool Tskhenis-Tskali

Lashadura tectono-seismogenic landslide

Guatemala

Seismogenic landslide

No data

200 people died.

Sweden. Gothenburg area

The landslide caused by heavy rains covered a distance of 100 to 175 m

3–4 million

67 houses were destroyed. 600 people were left homeless. 1 km of road destroyed. 60 people were injured. 9 people died.

Abkhazia. River pool Kelasuri

Kelasur tectono-seismogenic landslide

Revival of movements of the Holocene landslide, creating the danger of a large-scale collapse

Uzbekistan. Tashkent region.

Technogenically provoked (as a result of siltation of the Pskem River canyon) activation of the Bashkaragach landslide on board the bowl of the Charvak reservoir

Abrupt partial filling of the reservoir bowl and the formation of a high wave

France. Nice city

Underwater landslide transformed into a turbidity current

A part of the river delta is involved in the landslide. Var and the railway. Wave high 3 m spread over 120 km of coastline, damaging communications and harbors. 2 submarine cables were broken at a distance of 120 km from the city of Nice. Several people died.

Uzbekistan. Tashkent region

The Zagasan-Atchinsky landslide, technogenically provoked by the mining of a coal deposit and underground gasification of coal on the side of the river valley. Angren (on a slope at an altitude of 600 m). The displacement plane is located at a depth of 130 m.

Forced transfer of more than 2,000 houses to the opposite bank of the river. Filling 50 million m3 of soil to stabilize the landslide

China. Hubei Province.

Landslide (Yanchihe earth avalanche), technogenically provoked by the development of a phosphorite deposit

284 people died.

USA. California State. Area hall. San Francisco

Storm and catastrophe. floods caused several large landslides

No data

6,500 residential buildings, 1,000 industrial buildings were damaged or completely destroyed. enterprises and institutions. 30 people died.

USA. Utah

Landslide caused by melting snow and heavy rainfall

Record-breaking landslide in US history ($600 million)

China. Gansu Province.

Saleshan landslide caused by heavy rains

4 villages destroyed. 237 people died.

Chunchi landslide caused by heavy rains and rapid snow melt in the Andean highlands

150 people died.

Puerto Rico. Center. part of the island. City of Mamayes

Landslide caused by heavy rains.

129 people died.

The Reventador earthquake triggered the landslide of the same name

75–110 million

1000 people died.

Brazil

Petropolis landslide caused by heavy rains

300 people died.

Tajikistan. Gissar Valley

Several seismogenic landslides (as a result of the Gissar earthquake), the largest of them is 3700 m long, 600 m wide, up to 28 m thick

The liquefaction of the landslide mass led to the formation of a mudflow that advanced several kilometers, causing destruction and human casualties.

China. Sichuan Province

Hiksu landslide caused by heavy rains

No data

221 people died.

China. Yunnan Province

Touzahi landslide caused by heavy rains

216 people died.

Colombia. Cauca Department

Seismogenic Paes landslide caused by one. earthquake

No data

Covered area sq. 250 km2. 1,700 people went missing. 272 people died.

India. Himalayas. Malpa

Landslide caused by heavy rain

No data

221 people died.

Papua New Guinea. North-west coast.

Powerful seismogenic underwater landslide

No data

A wave arose, the victims of which were 2000 people.

Seismogenic landslide Ju Feng-er-shan

No data

At least 119 people died.

China. Tibet.

The Yangong landslide, triggered by the rapid melting of snow and ice.

500,000 people were left homeless. 109 people died.

Salvador. Suburb of San Salvador Las Colinas

Seismogenic landslide (epicenter in the Pacific region)

No data

4,692 houses were destroyed. More than 1000 people went missing. 585 people died.

Russia. Saratov region Volsk city. East slopes of the Volga Upland

Natural-man-made landslide in the center. parts of the city

321 families living in 237 houses were resettled

Sri Lanka

Landslide and mudflow caused by heavy rains

No data

24,000 buildings destroyed. 260 people died.

Pakistan, India (Kashmir, vicinity of Muzaffarabad)

Seismogenic landslides and rockfalls

80 million (Hattien Bala debris avalanche)

The avalanche blocked the channels of two tributaries of the river. Jhelum, village buried (1000 victims). In total, 25.5 thousand people died.

Philippines. Luzon Island. Albay Province

Landslides and avalanches caused by heavy rains (Typhoon Durian)

1100 people died.

China. Sichuan. Neighborhood of Chengdu

Seismogenic landslides, debris avalanches and mudflows

No data

20 thousand people died.

Egypt. East (upland) part of Cairo

Al-Duwaiqi man-made landslide as a result of construction work in the edge of the plateau

No data

107 people died.

Afghanistan. Baghlan Province

Seismogenic landslide

No data

More than 20 houses were buried. 80 people died.

Uganda. District national Mount Elgon Park (near the border with Kenya)

Landslide caused by heavy rains

No data

18 people died.

Japan. Honshu Island. Hiroshima

Landslide caused by heavy rains (204 mm of precipitation in 3 hours)

No data

Destruction in the city. Several people died.

Georgia. Tbilisi city

Landslide caused by heavy rains

No data

It blocked the Vere River gorge and caused flooding in Tbilisi. Mass death of animals at the Tbilisi Zoo. 19–22 people died.

Kyrgyzstan. Almalyk south of Osh

Catastrophic landslide

No data

Sri Lanka

Landslide caused by heavy rains

No data

180 people were left homeless. 7 people died.

*The table shows landslides that led to large-scale destruction (including on the seabed), or to numerous casualties, or to a fundamental negative change in the natural landscape.

The biggest collapse in the history of the earth

Most mountain falls occur in the spring. This is no coincidence. Autumn rains wet the rocks and water collects in their cracks. In winter, it freezes and at the same time expands, puts pressure on the walls, and pushes cracks apart. Thus, acting repeatedly, the ice “wedges” loosen the blocks and split them into pieces. Finally, the moment comes when individual parts break off from the parent rock and fall down.

Often the power of ice, acting quietly, is actively assisted by flowing waters. Washing the slope of the valley, they gradually undermine the ice, and at some point, under the influence of their own gravity, the washed away rocks collapse down and fill up the river valley. Mountain lakes appear in these places. An example is such pearls among lakes as Ritsa, Lake Sarez and many others.


Of all the collapses that occurred in historical times, the largest was Usoi; it occurred in the Central Pamirs in the area of ​​the former village of Usoy. Here, on the night of February 17-18, 1911, from the slopes of the Muzkol ridge, from a height of about 5,000 meters above sea level, a fantastic amount of earth and rock fragments fell into the valley of the Murgab River.

A strong earthquake was observed in the same area simultaneously with the collapse.

When scientists carried out a thorough examination of the area where everything happened and made the necessary calculations, it turned out that, firstly, the epicenter of the earthquake coincided with the site of the collapse and, secondly, the energy of the earthquake and the collapse were equal. This means that the collapse was the cause of the earthquake.

But the mystery of the Usoi collapse for a long time remained the question of its phenomenally large size. Until now, no one knows whether there has ever been a similar collapse on the globe in historical times.

Only after many years of research did geologists reveal the secrets of the Usoi collapse. It turned out that the strata that make up the mountain slopes are inclined towards the Murgab River valley. The mass of the rubble consisted of rocks that were stronger than those that underlay them. Over the course of thousands of years, the Murghab River washed away the steep right slopes of the valley, and thus their connection with the base was weakened.

The force of the impact of the earth and stones falling from a great height was so great that it generated a powerful seismic wave that circled the globe several times. It was recorded by all seismic stations in the world.

Record landslides

Unlike landslides, landslides originate from less steep slopes. Their movement occurs smoothly, calmly over hours, days and even months.

River water that has seeped deep into the earth's crust has a treacherous effect. It impregnates layers of loose sediments and moisturizes clays. Often such a moistened layer plays the role of a lubricant between the layers of the earth, and the upper layer, as if on a sled, begins to slide and float down. Small landslides are called “slides”.


MAXIMUM NUMBER OF LANDSLADE VICTIMS

On December 16, 1920, an earthquake caused a landslide on a mountain in Gansu Province (China), killing 180 thousand people.

MAJOR LANDSLADES IN RECENT YEARS

Several hundred people died on March 29, 1994, when persistent rains near the city of Cuenca in Ecuador caused a landslide that buried a mining village.

In June 1997, two landslides in gold mines in the Chinese province of Yanan killed 227 miners.

In September 2002, in the Karmadon Gorge (North Ossetia), more than a hundred people died, including the film crew of S. Bodrov Jr., as a result of the collapse of a huge glacier and landslide.

LANDSCAPE THAT SWALLOWED A CITY

The town of Saint-Jean-Vianny in the Canadian province of Quebec was completely abandoned after a landslide in May 1971. The city was built in the 17th century by the first settlers - in a secluded depression on the edge of a giant slope. Its inhabitants lived without any natural disasters for several hundred years. And on May 4, 1971, the first sign of an impending threat followed, when livestock refused to go out into the fields on the edge of the city: most likely, the animals felt minor vibrations in the soil. That same night, a huge landslide occurred. Roads, vehicles and houses were swallowed up by a huge wave of mud 15 meters high, which spread over 15 kilometers within three hours. As a result, 31 people died, and the city is still empty due to strong movements of the layers of clay lying underneath.

THE BIGGEST LANDSLAND IN ITALY'S HISTORY

The Piave River Valley is located in northern Italy and thanks to E. Hemingway’s novel “A Farewell to Arms!” familiar to millions of people. During the First World War, the Italian army was stationed here, operating against the Austrians after their defeat at Caporetto. On October 9, 1963, at 23.15, a terrible natural disaster occurred - the entire valley of the Piave River was flooded. There have been reports that the 260 meter Valmot dam has collapsed under the pressure of a massive landslide caused by the earthquake.

The world's tallest dam, more than 20 meters thick, withstood the earthquake. It collapsed a little later. As the surviving witnesses of the disaster recall, the roar that was heard before the huge water shaft collapsed into the valley had a different origin. It came from the mountains that had cracked on either side of the dam. There is testimony from Captain Fred Mickelson, the pilot of the US military helicopter that evacuated the residents of the village of Casso. The village stood above a dam and was in danger of residual landslides. He described the event as follows: “Behind the dam there was a lake about two kilometers long, but now it is no longer there. The tops of the rocks on both sides of the dam fell into the lake and literally filled it.”

The water forced out of the lake poured through the dam, destroying it, and poured into the valley of the Piave River in a giant waterfall 450 meters high at a right angle.

Longaron, a village located in the path of the water flow, disappeared instantly. 3,700 of the 4,000 inhabitants died. In Pigaro, only the bell tower, the cemetery chapel and one house survived. Until now, no one lives in the village.

THE WORST LANDSIDE IN EUROPE

For centuries, mountains of waste rock grew in the vicinity of mining towns such as Aberfan, in Wales (England), being an integral attribute of the mines. Due to their composition, such mountains are very unstable and mobile. In Aberfan, a stream flowed under the mountain, which, eroding the base, further reduced its stability. A few days before the disaster, local residents noticed some movement on the mountain and notified authorities.

On the morning of October 21, 1966, a representative of the municipal government climbed the mountain to check the information received. While he was inspecting the mountain, suddenly two million tons of rock began to move and fell on the city. The roar was heard several kilometers from the town. Rescue work began immediately, the miners rose to the surface and, together with the townspeople, began excavations. 43 people died - mostly children who were at school at the time.

RIVERS

"The Smoke That Thunders" or The Largest Waterfalls

This is how locals have long called the famous African Victoria Falls. The first European to see it was the Englishman D. Livingston in 1855. The traveler was sailing in a small boat along the Zambezi. The calm river suddenly changed: the water accelerated, became agitated, and somewhere behind the forest a frightening roar grew. Having barely managed to land on a small island, Livingston was amazed by the picture that opened: a wide river broke off, falling into the abyss.



How does such a natural phenomenon arise? Rivers make their way between different rocks. Some of them are easily and quickly washed away by water, others are difficult to wash away. And so it happens: somewhere in one place the river suddenly falls down, falling from steep, sheer ledges made of very strong rocky rocks.

Gradually, the water washes away the rocky ledge, the waterfall recedes up the river and becomes smaller. Over time, only thresholds remain - large pitfalls. Rivers with waterfalls are most often young. The age of rivers with rapids is already more advanced; and rivers that have erased all stone barriers along their path are old rivers.

For a long time, geographers believed that the Zambezi waterfall was the largest in the world. Then, in one of the most remote and inaccessible places on our planet, on the Churun ​​River in Venezuela, the world’s highest waterfall, the Angel, was discovered. Masses of water fall here from a steep stone wall about a kilometer high! It was discovered in the South American jungle by pilot D. Angel (Angel) in 1935. In the same South America, on the border of Brazil, Argentina and Paraguay, there is another waterfall - Iguazu; its width exceeds three kilometers. Strictly speaking, this is not one waterfall, but many. There are 275 of them here! It is impossible to take in the entire fairy-tale picture at a glance. Every second more than 12,000 tons of water rush down. Two large cascades stand out, falling from a height of seventy to eighty meters. The mass of water generates an air wave, which throws up light aircraft if they descend over the waterfall.

In North America, on the border between the USA and Canada, there is the well-known Niagara Falls. The river falls in two wide streams into a hole fifty meters deep. Businessmen use this majestic waterfall for profit. Niagara hosts all sorts of shows that attract crowds of tourists. In the 19th century, an unemployed American announced that he would swim across the lower rapids of the waterfall for a reward. In the presence of numerous spectators, he threw himself into the seething water, appeared for a moment in the middle of the river and disappeared forever among the foam and darkness. The unwitting hero turned out to be a seven-year-old boy, Roger Wood. In 1962, he was boating in Niagara with his uncle and older sister. The current capsized the boat, and all three found themselves in a seething rapids. They managed to snatch the sister from the water, and the river threw the uncle and nephew into a fifty-meter abyss. The adult crashed, but the child, unexpectedly for everyone, remained alive.

And one more interesting story. On March 29, 1848, Niagara Falls...disappeared! Every second, six to seven thousand tons of water fall into the abyss here. And suddenly everything stopped. Only small streams flowed from above. The rocks were exposed. More than a day passed, and the water came again. What happened? On the morning of March 29, 1848, a strong storm swept over Lake Erie, from which Niagara flows. She broke the ice that covered the lake, and large blocks of ice blocked the flow of water from the lake into the river bed...

There are waterfalls in Russia too. They are found in the Far East, Siberia, Karelia and the Caucasus. The championship in height is held by Ilya Muromets in the Kuril Islands - 141 meters. “The waterfall,” writes Yu. Efremov, “bursts out of the ravine, as if from a drainpipe, almost horizontally, bends in the air and falls freely. It turns out a vertical column of collapsing water, several meters away from the plumb wall... The wind, now stronger, now weaker, deflects the falling stream, and it bends now to the right, now to the left, as if alive..." In the Sayans (Eastern Siberia) "dancing water" attracts attention - Grandiose waterfall, two hundred meters high. It flows in cascades from the ice grotto.

In Central Asia, in the western Tien Shan, the Arstanbap waterfall is known, translated as the Lion's Gate. It falls in three cascades from sky-high heights - from a four-kilometer mountain!

The peoples of the world give beautiful, poetic names to “dancing water.” In Sweden there is the Hare's Leap waterfall, in Korea - the Seven Dragons, in Kyrgyzstan - the Pigeon Watering Place, and in the Caucasus - Maiden's Hair and Water Throat. The highest waterfall in India (252 meters) - Wonder Corner... Are all the waterfalls open yet? Probably not. Here is one of the newspaper reports from the end of the last century:

“A new waterfall was discovered from an airplane in the tropical jungle at a distance of 250 kilometers from the capital of Guiana. It is four times higher than Niagara and twice as tall as Victoria Falls. The newly opened waterfall falls from a height of about two hundred meters. They named him Kaleter."

The most unusual rivers

RIVERS PLAY HIDE AND HIDE

The Kara-Balta River flows from the Kyrgyz ridge, giving its waters to wheat fields, sugar beet plantations, and orchards. Examining its bed, scientists discovered that even before entering the valley, the river loses about a third of its flow. When they drilled a well, it turned out that this river was two stories high! Seeping through the pebbles and sand, part of its water formed, as it were, a second, underground stream.

In 1981, hydrogeologists established that across the territory of the Mari Autonomous Soviet Socialist Republic a large underground river runs parallel to the Volga, and in some places even adjoins it. It also happens that part of its path a river or stream passes on the surface, part of it goes underground.

In the Perm region, not far from the village of Kyn, the tributaries of the Chusovaya River perform such a trick: they seem to dive underground and then reappear on the surface. The place where they disappear is called dive by local residents, and where they come into the light again is called dive. The local river Kumysh has cut itself such a channel that for six kilometers it is almost invisible, and only then does it break out from under the rock and again become an ordinary river. In the Urals, about fifteen rivers, large, small and very small, are distinguished by such inconstancy - sometimes they are visible, sometimes they are not, hidden. The right tributary of the Kosva, the Gubeshka, is not visible for ten kilometers; the Vezhey River is hidden for eight kilometers.

One place is unusually beautiful on the South Ural River Sim, where it, encountering a rock on its way, disappears under it, its noisy running is again heard somewhere below, in the dense thickets of bushes.

A rare sight - a key on the right bank of the same river Sim, one and a half kilometers below the mouth of another river - Berda. It shoots straight out of the cliff, but it’s interesting that the water pours out in spurts: for about three minutes, vigorously, and then calmly for the same amount of time.

In Yugoslavia there is a river that first carries its waters in a narrow gorge, and then completely disappears into huge caves. Having walked a long way through the underground galleries, she disappears into a deep crack. Exactly - it disappears, because no one knows where it goes. They tried to find out with the help of dyes, but colored water was found in many springs around Trieste and even in the city water supply...

THE RIVER MAKES A CIRCLE

There is a river in the Gorky region with a curious name - Piana, a tributary of the Sura. And the river is interesting because its source and mouth are very close. Having run in a circle for more than four hundred kilometers, it reappears almost at the place of its birth and only then flows into the Sura. “Almost” is three dozen kilometers. And “running in a circle” is not entirely accurate. Wandering somewhere hundreds of kilometers, it makes so many zigzags and unexpected turns that it’s time to talk not about a circle, but about some other figure.

"NOVGOROD MIRACLE"

This happened a long time ago, in those days when Novgorod was an independent feudal republic and was called nothing less than Mister Veliky Novgorod. This event did not go unnoticed by the chronicler. Still would! After all, it concerned a person who occupied a prominent place in the church hierarchy - the bishop. In addition, this bishop, named John, stood at the head of the city council. What happened to him?

That year turned out to be difficult for Novgorodians: first, drought burned the fields, and then its eternal companion - hunger - fell on the city. The bishop, a lover of women, was blamed for everything: for his sins, they say, God sent misfortune. At first they wanted to drown him, but they changed their minds and decided to simply expel him from the city. They put together a raft, put the lascivious bishop on it and took him to the middle of the Volkhov - let him float with the flow! But the raft... didn’t want to go with the flow, but swam against it! One can imagine what was happening on the shore with the God-fearing Novgorodians. The chronicler (and, as we know, they were mainly monks) naturally interpreted what happened in the sense that God in this way condemned the little people who raised their hand against his servant.

However, it is doubtful that such a phenomenon as a river turning back was an isolated fact. It is even more doubtful that no one in the city knew the cause of this phenomenon. After all, in order to establish it, you just need ordinary observation, since cases when rivers and streams temporarily change the direction of flow are not so rare. This happens (and then, of course, it happened), for example, on some lowland rivers during spring floods: a large river “locks” the tributaries, and then they either stop and overflow, or even flow backward for some time.

Well, in Novgorod everything is explained even more simply. Volkhov, in essence, is a natural, miraculous canal connecting two large lakes - Ilmen and Ladoga. The river is full-flowing, with a slight natural slope. In the year of the “Novgorod miracle,” there was a dry summer in the upper reaches of the Volkhov, and the level of Lake Ilmen dropped. It was enough for heavy rainfall in the lower reaches, that is, over Ladoga, for the Volkhov flow to slow down or even turn back for a while.

By the way: the Greek river Avor changes its flow direction regularly, in the rhythm of fluctuations in the level of the Aegean Sea caused by ebbs and flows.

THE FUNNIEST NAME

The funniest name, of course, goes to a small river in the Vologda region - Kuku River. “Shouldn’t we go fishing on the Kuku River?” You can also do your laundry nearby – in the Portomoyka River.

The largest ravine on Earth

If we abstract from everyday life, from our petty worries and passions, then we can say that on the edge of the Grand Canyon of Colorado you clearly feel the breath of Eternity. And you realize the insignificance of the segment of existence allotted to us. And you feel like a speck of dust in the grandiose temple of the Universe.



The Grand Canyon is a huge ravine 350 kilometers long, dug by the Colorado River into the layered sedimentary rocks of the plateau of the same name. Its width in the upper part is 8–30 kilometers, at the river’s edge it is less than 1 kilometer (in some areas up to 120 m). The depth in some places is up to 1800 meters. The steep, sometimes highly dissected slopes are replete with bizarre protrusions in the shape of bastions, columns and pyramids. The river cuts through horizontally lying layers of rocks: from Archean crystalline to Upper Paleozoic sedimentary - limestone, sandstone, shale, etc., having different colors. The canyon was formed in the Cenozoic as a result of river erosion, intensified by the gradual rise of the plateau. The Colorado River in the Canyon has an average drop of 1.5 m per 1 km and flows at speeds of up to 25 km/h.

During high water, a river can transport about two million tons of silt in a day - it colors its waters, and 20 percent of pebbles and gravel must be added to this huge amount of abrasive material. Therefore, it is not surprising that over millions of years the river completely removed 12 of the top 25 layers of sandstone, limestone, shale and other sedimentary rocks along its path, and deeply cut through the remaining layers. 225–280 million years ago there was an ocean in this place, but over the past geological epochs it was repeatedly replaced by desert. Layers of multi-colored ocean and wind-blown sediments are cut through in places by lava flows of ancient volcanoes. On this thickness of stone pages you can read the entire geological history of the continent and draw conclusions about climate change.

The surface of the plateau, once the floor of an ancient ocean, was the uppermost of many layers of sandstone, shale and limestone laid down during the Paleozoic era, 600–250 million years ago. These rocks were deposited on top of even older crystalline schists formed in the Precambrian, 2 billion years ago.

According to various estimates, it took the river from 1.7 to 9 million years to carve this giant gorge. If we take average figures, it turns out that Colorado carried 2.5 billion cubic meters of rock into the ocean every year, and the erosion rate was a meter deep per thousand years.

People settled in the Grand Canyon at least 4,000 years ago. In 1930, rock carvings (petroglyphs) of the ancient inhabitants were discovered here; The subjects were mainly animals. Earlier than 500 BC. e. In the Canyon lived small groups of semi-nomadic Indians from one of the desert cultures, characterized by basket making. Their dwellings were carved out of rock or made of clay. Then the territory was occupied by Indians belonging to the Anasazi archaeological culture. They hunted deer and cougars, and grew corn, pumpkins and beans in the side branches of the canyon. And at the end of the 10th - beginning of the 11th century AD. e. Pueblo Indians lived here and built stone houses. A century and a half later they were replaced by the ancestors of the current local tribes.

Around 1540, Spanish conquistadors led by Francisco de Coronado came here in search of gold, but, standing on the edge, they bypassed the inhospitable gorge. Apparently, they gave the name to this unique geological formation (canyon - translated from Spanish as “chimney”). In 1776, the Spanish missionary Father Garces entered the canyon to convert the Havasupai Indians to Christianity. They did not convert to Christianity, but Father Garces left his mark here: he gave the river the name Colorado, which in Spanish means “colored” or “colored.”

In 1848, after a successful war with Mexico, the American government claimed these lands as its own. Lieutenant Ives, who commanded a party of military surveyors who explored the area in 1858, wrote in his report: “We were the first, and most likely the last, party of white men who ever visited this completely useless, bare country. It seems to have been destined by nature that the Colorado River should flow undisturbed throughout most of its lonely and proud course.”

The first person to cross the Grand Canyon on the Colorado River and survive was John Wesley Powell. This significant event took place in 1869. Powell was the first to study and describe the remains of the Canyon Indian civilizations. After this expedition, which took place in 1869, American interest in the unique monument of nature and history grew. However, this attention resulted in drama for the local tribes. After deposits of lead, zinc, asbestos and copper were discovered here in the 1870s, the Indians were forcibly moved to reservations.

Later, despite the economic benefits of mining the Canyon's minerals, preference was still given to the development of tourism. The first tourist groups visited the valley as early as 1883; By the beginning of the 20th century, a railway was built here. In 1919, Senator Harrison introduced a plan to create the Grand Canyon National Park; then US President Wilson supported this proposal. Since then, the status of the Canyon has remained unchanged. Its area is almost 500 thousand hectares.

After 1919, the Grand Canyon was visited by approximately one hundred million tourists. In 1979, the canyon was included in the list of “sites of world significance” compiled by UNESCO.

Athletes from all over the world come here to raft the Colorado, overcoming more than a hundred rapids in canoes, kayaks, paddleboards, rubber boats or rafts. Classical music concerts are held in natural caves located in some places in the walls of the gorge - the acoustics here are excellent.

To the unaccustomed eye, these harsh places may seem lifeless, but the Grand Canyon contains many plants and animals. On the bottom, where it is dry and hot, you can find a variety of desert creatures, such as the spotted skunk, yellow scorpionfish and whip-tail lizard. Purple ferrocactus and mesquite trees grow beautifully here. The brush-eared Kaibab squirrel is found only on the north side, while the Abert's squirrel prefers the warmer south. The cool slopes of the canyon provide shelter for Arizona gray foxes and rock chipmunks. Mountain lions also roam the rocks, but there are very few of them left, just like the people who once lived here. Tourists flown by helicopter to Havasu Canyon to see the remaining Havasupai Indians are seeing the last of the area's original inhabitants.

Where the Colorado bursts out of the Grand Canyon on the Arizona-Nevada border to form 115-mile Lake Mead, sits the Hoover Dam, the largest dam in the world. It was built between 1931 and 1936 and named after former President Hoover in 1947. The dam was built at about the same time as the first stage of the famous Soviet Dnieper Hydroelectric Station (1927–1932). Its height is 220 meters, and its thickness at the base is 180 meters (the height of the Dnieper Hydroelectric Station is 60 m). The Hoover Dam is far from the only one built on the Colorado River along its entire length, but it is the largest.

Its power plant capacity is 1.25 million kW, and it irrigates vast areas of Northern California, Arizona, Nevada and New Mexico. It is also a source of energy and water for the entire region. This is exactly how it was conceived – as multifunctional. The latest technologies were used in the construction of this hydraulic miracle. The dam, begun during the Great Depression, provided jobs to tens of thousands of unemployed Americans. And although work on the dam was fraught with great risk, and over five years more than a thousand people died during its construction, the influx of labor did not become scarce.

In total, along its 2,333 kilometers, the Colorado River rotates the turbines of 30 power plants. Dams hold back the flow of the river, silt and other abrasive materials settle at the bottom of the reservoirs, and further deepening of the Canyon has virtually ceased. However, the river can wait: what is two or three centuries, during which the dams can stand, compared to millions of years?

Based on materials from Yu. Ryazantsev
HAVE SCIENTISTS REVEALED THE ORIGIN OF THE GRAND CANYON?

The rocks in which the Colorado River carved the Canyon are composed of sandstone that hardened about 150–300 million years ago. Where so much sand came from in these places remained a mystery.

According to research conducted by Bill Dickinson and George Gehrels of the University of Arizona in Tucson, at least half of the hardened sand of the Grand Canyon was once part of the Appalachian Mountains, which stretch along the east coast of the United States and are located several thousand kilometers from the Grand Canyon. According to scientists, sand came to the west along with powerful river flows. Then it settled in the territory of modern Wyoming, after which it was carried south along with the winds, where it turned into dunes.

In their study, the scientists used the uranium-lead dating method. The sand rocks contain particles of zircon, a mineral containing uranium. Once the zircon crystallizes out of the liquid magma, the uranium begins to decay and the uranium naturally turns into lead. The amount of lead in zircon particles allows us to determine the age of the zircon. The age of zircon particles from one mountain range can then be compared with the age of zircon from other mountains.

Half of the zircon samples taken from the Grand Canyon formed either 1.2 billion years ago or about 500 million years ago. This age coincides with the age of granite in the Appalachians. Only a quarter of the zircon particles match the age of the Rocky Mountains. Also, a small amount of sand came to the western United States, apparently from Canada.

This method has proven effective in determining the route of movement of tectonic strata across the Earth's surface. By comparing the age of zircon in the sandstone of one continent with that of zircon in the mountain ranges of another, reliable evidence can be obtained that the two continents were once one.

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