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Home > Articles scientifiques > Géophysique, géographie > Météorologie et climatologie > Greenland’s glaciers

Greenland’s glaciers

Gaston Tissandier, La Nature N°43 — 28 Mars 1874

Mis en ligne by Denis Blaizot le Wednesday 15 October 2014

All the versions of this article: [English] [français]

It is no longer the actual mode of formation of glaciers, and the actual properties of the solidified masses of water are known to scholars ; it is a scientific glories of Professor Tyndall , to have been able to determine the role these wonderful solid play in the shallow reservoirs mechanism of our spheroid. This is the work of Mr. Tyndall as anyone bear the stamp of genius ; If confirmed every day by new observations, which give them a relief imposing, and produce sharper, more important. The fine studies of the English scholar, executed in part, as those of the great Agassiz, in the midst of Alpine glaciers have recently been continued on a much grander stage, the imposing theater icy fjords of Greenland. These are the theories that guided Mr. Tyndall intrepid American, Mr. Dr. I. J. Hayes, already famous for an amazing campaign in the polar seas, amidst the majestic glaciers of Greenland. He checked there already professed doctrines today by physicists, but documents and illustrates that the young sailor recounts his summer trip to Greenland, offer an unexpected interest in revealing the tremendous power acquired by glacial phenomena on the old Green Land of old Normans.

Greenland once enjoyed a sweet and mild climate ; Sea ice that is gradually formed in the continent, which has been growing each day under the influence of abundant fall of almost continuous snow, gave birth to the glaciers in the mountains of ’frozen water, giant cliffs, whose woodcut reproduced against the majestic appearance. This glacier Sermitsialik that American explorer especially visited, is only an arm of the great heap of solid water that is now a large part of Greenland. We see what a contrast it presents with ice fields that reproduces the second drawing, as the first from the work of Dr. Hayes. Greenland as in the Alps, it is the snow that had fallen from the clouds, high vapor ocean under the action of sunlight, and transported to the polar regions by air movement, which in the game the refreezing, turns into clear ice. But the phenomena are here singularly multiplied. « The Greenlanders continent has an average of 200 myriameters [1] long and 100 wide, that is to say, 20,000 square myriameters ; rated very moderately to 165 meters depth of the ice that covers [2], we have for the total volume of frozen water a figure of 550 trillion cubic meters, almost at first sight fabulous result. »

Greenland as in the Alps the surface snow on the hills, is white, dry and light ; at a lower level, it is a little harder, less flaky, slightly agglomerated. In the underlying regions, ice, completely transparent and crystalline. A solid and transparent state, the ice in Greenland is in truly magical aspects ; it forms inimitable buildings, bizarre, outrageous even, as only nature can do : sometimes cc are elegantly carved arches, and caves formed with art ; sometimes, they are massive clusters imitating the Egyptian constructions. When the sun shedding light over the palaces of nature, they are adorned suddenly pure and cool shades, clothe fantastic and brilliant iridescence, ranging from emerald green to sapphire blue. Then the columns shine like gems amid massive serrated, and the observer dazzled by these incomparable riches feels transported into the world of dreams !

Dr. Hayes emphasizes his personal observations, which are completely in agreement with those of Dr. Tyndall, on the passage of the opaque white color of the glacier at the top, the transparent blue color that has on its part lower. Snow falling in the high regions, crowding on the shoulders of giant ice is dry ; In this state it can not be transformed into ice. But when the summer arrives, sunlight partly based the surface layer ; the water produced flows into the interstices of the cold mass of the lower blocks, and it will form the next jelly solidifying the glue that unites them. As for the color and transparency of the ice thus formed by snow, it is explained very clearly by Professor Tyndall. The transparency is due to the absence of air in the ice homogeneous ; the opacity of a snowdrift, the interposition of an infinite number of bubbles. « The white, says the English scientist, is always the result of irregular and intimate mixing of air and a transparent solid. Reduce to a fine powder the most transparent rock salt, we will have the same salt best pure substance ; The colorless glass give us, pounded an equally white dust ; a diamond sprayed resemble snow. Here is the reason : when light passes from one substance to another that has a different refractive power, a portion is always reflected, therefore, when light falls on a transparent air mixed with solid, part is reflected at each passage of air to the solid, and the solid was air ; when the solid is a finely powdered body, this phenomenon is repeated so many times that the passage of light is virtually stopped. Thus, the mixture of two perfectly diaphanous substances gives us an opaque compound ; the intimate union of air and water produces foam. The opacity of the clouds is an effect of the Act ; condensed steam locomotive throws his shadow on the fields adjacent to the road because the sunlight is broken, returned »echoes« by countless surfaces offered by molecules of water and air. »

Thus mountain snow arrives without completely melting, forming the sheer ice, and bring forth the natural ice of prodigious size. These solid water tanks are staggered at all latitudes, but the lower limit rises somewhat regularly above the sea level, as, out of the polar regions, we get closer to the equator. According to Dr. Hayes, the line of perpetual snow is located at 61 ° N, 800 meters above the sea level ; 69 ° is approximately 550 meters ; 78 °, 160 meters ; between 80 ° and 82 ° it touches the surface of the sea, and do not allow any trace of vegetation to occur.

In Greenland, better than on the summit of the Alps, there is the real ductility of glaciers, the substance, similar to soft wax, flows gradually to the lower regions, as would a thick molasses. The glacier appears as a real frozen river, which has its current ; but while the Alpine glaciers flow at a speed of 0.10 m to 0.33 m per day, they walk more slowly in Greenland, where speed seems to vary between 0.07m and 0.20 m in the same time.

Alpine glaciers, sliding into warmer regions, melt and disappear « as would the end of a tallow candle ; »Greenland on the contrary, water clusters solidified never go down in a warm environment for them to melt. We see them slide down the mountain and arrive majestically in the waters of the sea ; there they divide, and carried by the currents they are icebergs : these huge ice pans lead off the earth and the rocks they have trapped in their substance. The glaciers of the Alps, such as Greenland, and achieve the same goal by different routes. « The mountain snows return to the ocean, their homeland. »

The volume of the Greenland glaciers is sometimes enormous ; This is an inexhaustible mine of icebergs. Dr. Hayes has measured that had more than 100 kilometers wide, which formed in the sea a wall of cliffs 100 meters high. The crystal wall sometimes descends to the bottom of the ocean, that is to say up to 700 meters below the liquid surface. What terrible block, what prodigious pile of snow !

On some parts of Greenland, the American explorer observed glaciers actually slip into a bed made of rocks, and completely affect the appearance of a river. Instead of water flowing quickly is ice, which slowly rolls his crystal. Instead of hauling trees and woody debris, the river carries solid rocks. But as the river of water, the glacier in Greenland has rapids, waterfalls, waterfalls and cataracts. Near the fjord Sermitsialik, Dr. Hayes discovered a large icefall which yields nothing like grandeur and beauty as in the famous cataract of Niagara. Water is only replaced by crystal stalactites !

Despite these incomparable curiosities, it is amazing to learn that the appearance of the icy regions of the former Green Land is usually sad ; this land, it seems, deserves the name of Desolation Land that gave him browsers. « I’ve never walked the deserts of frost, says Dr. Hayes, without deep emotion and almost solemn. It shows both so much and so little ! Nothing comes divert the mind from the contemplation of a single force, in the forest, life in its various manifestations are encountered ; at the seaside, we look towards the wave motion is meant to breathe the ocean ; Nowhere does the idea focuses on a single agent isolated lonely. Here boundless desolation of the Sahara Snow takes almost a terrible look ! ... »

We will not dwell on the quaintness of the Greenland exploration ; this is not it uninteresting, quite the contrary. The history of ancient and terrible fighting that once supplied the old Green Earth after the discovery of a strange region, the gentle manners of the present inhabitants living in vicinity so little known to the European world and offer the traveler a touching hospitality, so affable, are for Dr. Hayes as many striking subjects that can exploit real writer. But we do not follow the explorer in all his stories. We just want to present its journey under a special face, and show that the new expedition provided the Earth Physics rich of valuable observations contingent, which fully confirm the modern concepts on the mechanism of glaciers on the surface of the Earth.

Gaston Tissandier

See also the Arctic Ocean. Voyages of exploration to the North Pole, by I. J. Hayes, abbreviated H. Vattemare. Hachette 1886

[11 myriametre = 10,000 meters

[2Currently, it is estimated the thickness of the ice cap of Greenland to almost 3 000m

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