Libmonster ID: RU-17280
Author(s) of the publication: Vladimir ALEXEYEV

by Vladimir ALEXEYEV, Dr. Sc. (Geogr.), Geocryology Institute, RAS Siberian Branch, Yakutsk; Geography Institute, RAS Siberian Branch, Irkutsk

Today everything seems to be explored on earth. Not in Siberia, though. Siberia is a vast land stretching for thousands of kilometers all the way from the Urals in the west to the Pacific Ocean in the east. This land has many mysteries to it; one is that of the Patom crater (cone) in the Irkutsk region. This crater is named after two tributaries of the great Siberian river, the Lena-the Big and the Little Patom. For years the Patom crater has been attracting researchers involved with the earth sciences and botany-even mathematicians find it "groovy". A great many hypotheses have been advanced concerning the origin of this striking natural phenomenon. And yet it is still a mystery. In the opinion of the author of the present article, the Patom cone is a geocryological structure related to hydrovolcanicity--eruption of matter in frozen water-bearing systems giving rise to hummocks of swelling (bulging), the hydrolaccolites (called bulgunnyakhs in Yakutia, and pingos in Canada).

стр. 54

THE NEST OF THE FIERY EAGLE

It happened in August of 1949. Vadim Kolpakov, a young geologist surveying deep in the woodlands on the border of Yakutia and the Irkutsk administrative region, came upon an odd object that looked like a waste pile, a truncated cone with a hollow on top. It stood out in the locality as "whitish" and "rather young". Two years after, Kolpakov described his impressions in his contribution to the journal Priroda (Nature). "Coming up, I saw this quaint hill was not a human handiwork. Rather, it resembled an ideally round neck of a volcano, 70 meters tall, the height of a 25-story building... That natural anomaly, I guessed, was between 50 to 200 years old. Climbing up to the crater's ring bank, I discovered a semicircular 15 m dome right in the center of the trough... Talking to Yakut hunters, I learned this place was known as the Nest of the Fiery Eagle. No one could tell why. There are no anomalies like that anywhere in the world." Earth scientists called it a Patom crater (also known as the Yavaldinsky or Jebuldinsky crater).

Sergei Obruchev, an eminent earth scientist of the day who had for years been working in this country's east, made this comment: the crater located 300 km from the community of Bodaibo was an eruptive (volcanic) structure produced by plutonic gases breaking to the surface locally, on a site slackened by tectonic faults.

Although the origin of the crater was discussed now and then in the literature during the 1960s, this phenomenon was handled rather matter-of-factly. Yet in these last ten years the Patom crater riddle has come to be looked upon as something sensational.

A large group of scientists from this country's lead research centers have launched thorough investigations of this spectacular natural phenomenon. All in all, seven field parties went there (the last one, in the summer of 2011). They have drawn up the first geological map of the cone and made surveys (magnetometric, matallometric and gravimetric, too). Also, tree samples were sawn off for dendrochronological assays to learn the age of trees in the vicinity; these explorations were supplemented with quality aerial photos.

HYPOTHESES AND POSSIBLE SCENARIOS

At least a score of different versions have been suggested in the literature and electronic media about the origins of the Patom crater. All these hypotheses may be broken down into four categories: the cosmo-, litho-, an-thropo-and cryogenic ones. The cosmogenic, or space-related factor, involves extraterrestrial causes, such as ET substances, forces and even civilizations. Thus, Felix Chernousko, RAS member and head of the RAS Institute of Mechanics Problems (his worker collective has created a physical model of the Patom crater), believes the conical depression on top of the truncated cone was formed by an impact of a heavenly body (meteorite?). Other hypotheses take us back to the Tunguska disaster of 1908, supposedly caused a large celestial body that hit the forestland in the basin of the Lower Tunguska to send

стр. 55

Geologic map of the Patom crater (V. Antipin, A. Fedorov): 1--massive crystalline limestones with quarts/muscovite/carbonate veins (ring trenches); 2--massive fine crystalline limestones with quartz veins (late ring bank and central hillock); 3--eroded limestones with solitary blocks of metamorphosed sandstone and schist (southern part of the central hillock); 4--eroded limestones with gruss (landwaste) and lumps of metamorphosed sandstone and schist (early ring bank); 5--talus (hillside waste) of rock on the outer slope of the cone; 6--enclosing limestone of the Proterozoic Mariinsk suite; 7--sandstone interlayer amidst sandstone; 8--metamorphosed sandstone; 9--ring and radial fault zones in and around the crater; 10--modes of rock occurrence.

a seismic wave that traveled round the globe three times. Possibly some part of that bolide struck the Patom crater as well.

Advocates of the lithogenic theory point to processes occurring in the lithosphere, the upper part of the earth shell, and even down in the mantle. Endogenic (internal) processes there cause rock extrusions at high pressure. This may be a heating of uranium-containing substances (which means there may be major deposits of radioactive matter deep under); or a violent ejection of methane; or decomposition of gas hydrates (which indicates the possible presence of petroleum and gas); or formation of a "young" kimberlite (diamond) pipe (which means there might be diamond deposits under the Cambrian sedi-mental rock); and last, migration of fluids through fissures, faults and tectonically slackened zones.

Adherents of the anthropogenic hypothesis say the human factor could be implicated (they point to underground nuclear tests, construction of mines and bunkers, and other activities underground).

The "cryogenists" point to the cold factor, namely the freezing of the upper earth shell and associated phenomena like subterranean glaciers and sudden crystallization of the supercooled underground waters. Most of these versions proceed from the trivial fact: the volume of a fluid expands with its crystallization; some scenarios are rather far-fetched--at variance with the physical laws or else based on phenomena unknown to geocryologists and glaciologists. To get to the heart of the matter I think it should be considered from positions of the contemporary cryological science.

THE ROLE OF CRYOVOLCANICITY

It is a fact: the freeze-in of loose water-saturated rock results in its spatial or localized swelling (bulging) with solitary or cluster-like effusive forms of relief features like hummocks, ridges and cones. In keeping with the principles of physical similarity this process can justly be defined as cryovolcanicity (cryogenic volcanicity), given such essential conditions as the presence of water or wet ground mass, multiple temperature fluctuations below zero centigrade.

Here on earth cryovolcanicity takes different forms. One such form is cryogenic microvolcanicity manifest in the crystallization of drops of water either suspended in the air or sedimented on the surface of ground and above-ground objects. Drops of sleet are an ocular example as particles of water are ejected from under the ice envelope to freeze in the form of hummocks, cones or sinter terraces. Cryogenic meso- or midvolcanicity takes place

стр. 56

Geocryological section of a bulgunnyakh at Khotonok off the Alalakh community in Yakutia: 1--sand; 2--loam; 3--sandy loam; 4--injected ice; 5--ice-and-ground; 6--isotherm, oC.

with the freezing of brooks, rivulets, pools, hollows and dents in terrain features, on paved roads or on ice. As to cryogenic macro- or high-level volcanicity, it is characteristic of large bodies of water, such as lakes, ponds, lagoons, canals, and the like. Cryogenic macrovolcanic-ity also occurs in the upper earth crust. Taking place in harsh climate areas, it gives rise to ice bodies of surface and underground waters, ice and ground hummocks of swelling, mudstreams and mudflows, gas and water fountains... Cryogenic mega- and even gigavolcanicity (super-volcanicity) is possible on some planets of the solar system either on the surface or deep under as great pools of water or other liquids freeze. One such example is the Nix Olympica cone on Mars located by the American Mari-ner-9 probe in 1971 (its base diameter, 500 km; height of the crater, 27 km; crater, 40 km across). Here on the globe cryogenic mega- and gigavolcanicity may occur with the disastrously blitz freezing of large lakes, seas and oceans.

The Patom cone, as I see it, is one such form of cryogenic macrovolcanicity. It is a typical hummock of bulging (bulgunnyakh, pingo, hydrolaccolite) formed with the freezing of water-saturated strata.

Mikhail Sumgin, a foremost permafrost expert, explained still in 1927 the cause of localized upthrustings of open systems. He did it by citing a simple experiment with a small amount of crystallizing water. His pupil and follower, Valerian Petrov, extended this explanation to closed structures. Exploring the ice mounds off the Amur-Yakut highway, Petrov was the first to notice this phenomenon: the growth of bulging hummocks occurs in consequence of a vacuum formed at the lower boundary of frozen ground as ice thaws out at rising temperatures above ground by day. The vertical movement of frozen layers sets in with some time lag after yet another cold snap when the interlayer of water is crystallized (this water pumped up from lower horizons). Much later, in 1988, Dr. Grigori Feldman reproduced this process in freezing chambers of his research center (Melnikov Institute of Geocryology, RAS Siberian Branch); lately Dr. Yakov Gorelik of the Institute of Cryosphere of the Earth, RAS Siberian Branch) reaffirmed that experimentally and in mathematical models.

Even experts are staggered by the scope of annual hum-mocking and bulging in the cryolithyozone. In cold regions during wintertime the ground surface rises by 0.2 to 0.5 meters almost anyplace, and it sinks as much in summertime. In the vicinity of wellsprings the frozen ground often bulges, cracks up and bursts to rise as high as six meters (!) in just one season. Such mounds explode time and again to give vent to gases, water and mud streams bursting forth from lower strata.

Mounds of swelling (bulging) formed over many years are found throughout the frozen rock propagation area. The largest rise in the maritime plains of the North. All

стр. 57

the way back in the 1930s Dr. Vladimir Andreyev, an eminent paleobotanist, reported knolls of bulging, 1 to 70 meters tall, discovered in the West Siberian Plain and thought to be hundreds and thousands of years old. Andreyev said the West Siberian bulgunnyakhs (hillocks), in no way different from those in Yakutia, rose up as subla-custrine taliks (patches of thawed-out rock amidst frozen ones) froze up again. The same conclusion was made in 1938 Alf Earling Porsild, an American botanist and North explorer, who observed a pingo (knoll) rising in the Mac-kenzee river delta in Canada, on the site of a lake drained off in 1900. This knoll started growing 30 years after the event. As his colleague Ross MacKay demonstrated later, from 1930 to 1980 it added yet another ten meters, with as much as 29,700 m3 of ice formed inside (or close to the volume of the knoll).

The cryogenic origin of solitary hillocks in maritime plains and mountain river valleys in the zone of freezing is indisputable. But do such forms of relief arise with the freezing of bedrock? We shall try to clear it out.

FORMATIVE MECHANISM

The upper earth shell is crisscrossed by numerous cracks, fissures, grooves and channels, either open or closed depending on the depth of occurrence, degree of fragmentation and composition of rock. Usually the zone of open jointing is located above the local base line of erosion. It is intensively blown through by variable (upstream or downstream) air currents and washed through by atmospheric precipitation seep-in. The fissures and pores of the lower hydrodynamic zone are filled with water as a rule. Over many years of freezing both zones iced up: the upper zone filled with sublimated and sinter (fresh) ice, and the lower one, with massive congealed ice. The rock mass thereby turns into a water-resisting monolithic stratum forming an intricate configuration of watery taliks of the open or closed type. The latter may disappear or get formed anew changing in size, configuration, and in the volume and chemical composition of water.

The largest number of cavities is formed in karsting carbonate and saliferous strata, namely in lime- or chalk-stone, dolomites, and halogens. An involved network of channels permeated the rock stratum in the process of sedimentation and metamorphosis of the sediments. In the permafrost zone the cavities of the upper hydrodynamic zone are iced up periodically, their walls (frozen in full or partly) split, cave in; in the lower zone ice fills caves and interconnecting passages. The Heetei Cave east of Lake Baikal described by the German explorer Johann Gmelin way back in 1735 may serve as a good example. Rising at its mouth is a hill much like a bulgunnyak knoll. During cold spells this cave might be filled with water and

стр. 58

Shorthands of knolls of bulging with the freeze-in of open (a, b) and closed (c, d) cryohydrogeological structures: 1--melt (not frozen) aquaferous rock; 2--seasonally frozen and thawing ground; 3--perpetually frozen rock; 4--underground ice; 5--air cavity deep within the ice core; 6--thermokarst lake in place of the knoll of bulging; 7--course of subterranean water movement within a frozen hydrogeological structure; 8--vector of maximum cryogenic bulging of ground and ice; 9--diagram of the rate of movement of an ice-and-ground mass in a big knoll of bulging; 10--outer contour of a hydrolaccolite in a stage of its maximum growth and in periodical ground freeze-in and freeze-out; 11--water level in the lacustrine hollow filled in full; e--postcryogenic structure formed upon rock degeneration and collapse of the knoll of bulging.

freeze all through, and this resulted naturally in the disintegration of enclosing strata, and in the upthrusting of crushed and jointed rock.

Heetei is just one among thousands of ice-filled cavities west and east of Lake Baikal, in the Sayan Mountains, in the Altai area, west of the Urals and elsewhere in the cryolithic zone. The sedimentary cover of carbonate rock of the Siberian platform (with the Patom cone in the center) has seen all possible transmutations of speleogenesis (cave formation); in the Late Cenozoic it froze through and thawed out time and again. Recently, in 2011, Sergei Fotiev, expert in geocryology and hydro-geology, described the evolutionary pattern of this land. Proceeding from his data, we can visualize the Patom cone formative conditions.

Towards the onset of the first cryogenic epoch of the Pliocene (that epoch took just 20,000 years, about 3.1 to 3.08 mln years ago), the terrigene-carbonate pores of the Proterozoic Mariinsk suite that built the cone had already been karsted up and crushed by tectonic shoves along the fracture of the Patom crater valley. The frozen sedimental-metamorphic strata were not deep and could have hardly caused any substantial transformations of water canals. But there occurred multiple and dramatic changes of the hydrogeological basin's structure in the subsequent epochs, namely in the second Pliocene (350 thous. years ago) and especially in the third Pliocene-Holocene epoch (1.92 mln years ago) with over 20 years of freezing and as many years of thawing in the absence of permafrost. During still another cold spell (ca. 3500 to 3000 B.C.), this basin froze to great depths (presumably down to the crystal base), it did not thaw out in a sequence of further warming spells, with taliks produced as a result. In the following freeze-in periods (ca. 300 years B.C., 1500 years and 300-500 years A.D.), the aquiferous (water-bearing) talik on the site of the Patom cone did freeze now and then, though not in full possibly. Blocks of rock were broken and crushed, with ice-and-ground breccia and separate fragments extruded thereby--this is how a knoll of bulging rose on the ground surface.

Explosive processes should not be excluded either, single and multiple, triggered by instantaneous crystalliza-

стр. 59

tion of supercooled water enclosed in the "inner aquatic core". Upon explosion the ejected debris was congeled to produce loose curum* deposits on the cone's surface. The kettlehole, billows and hillock on top of the knoll indicate the cyclic thaw-freeze pattern of the discharged mass; this is confirmed by on-the-spot observations of similar structures elsewhere.

The sink (conical depression), ring banks and the hillock could be formed without the water core's thawing in the process of linear distending movement of ice-and-ground masses, traveling in much the same way as the frontal scarps (edges) of stone glaciers. The cone's mass containing a large amount of intraground ice is capable of plastic deformations (gentle flow), as proved by the overthrusts of clastic stuff on the plant cover at the crater's foot, by the buried remains of trees and bushes, and by the goffered and scalariform (step-like) surface of slopes and depressive relief features. If the rate of vertical ground shift exceeds that of ice-and-ground diffluence, the knoll will grow up and take on a tapered apical form. But if the ejection rate is below that of distending movement, the cone will be truncated in form and lower in height, with the diameter of the volcanic funnel (cone) getting wider. The asymmetry of the Patom crater is prove positive of such geological evolution: its slope overlooking the valley is elongated and more gentle than the op-

* Curum, in local Ural and Siberian parlance, stone or rock stream.--Ed.

posite, mountain slope. The change of the level the ring banks on top supports this evidence.

According to Kolpakov, the truncated tip of the cone was strictly horizontal still in 1949. Dr. Alexei Portnov surveyed the object in 1961 and published its schematic profile; its slope facing the valley was markedly lower than the mountain one. In 2011 Ivan Ugryumov and Dmitry Demezhko of the Geophysics Institute (RAS Ural Branch) found the absolute height of the outer side of the bank to be 12 m lower than the opposite edge, that is the plane of the conical section was inclined toward the valley of the Ekssökülyakh rivulet.

So, the version of the cryogenic origin of the Patom crater is well-grounded and quite in keeping with theoretical, experimental and on-site evidence. But why just one cone in the Bodaibo woodlands, and no cones like that elsewhere in Siberia and on other continents?

HOW MANY HYDROLACCOLITES ON EARTH?

Geocryologists know of many Patom crater analogs along the arctic belt built of loose Quaternary deposits. Thus, Ross MacKay has mapped as many as 2,000 pin-gos. North America's arctic coast has about 5,000 knolls of the bulgunnyakh type, with 25 percent in the Macken-zee river delta. In Greenland as many as 1,500 knolls of bulging have been registered. Around 200 hydrolaccolites are on the floor of the Beaufort Sea, an extension of the

стр. 60

Arctic Ocean north of Alaska and northwest Canada. Such knolls are also found in Eurasia, in the plains of the North, in Franz Josef Land as well as in Kazakhstan, in the Tien Shan Mountains, Mongolia, and Tibet, that is wherever there is perpetually frozen ground. Hundreds of collapsing mounds of bulging of the pingo kind are identified in Western Europe, the holdover of the latest continental glaciation.

Many of the burial kurgan mounds beyond the present permafrost area (archeologists say there are thousands) may be not hand-wrought at all, but rather, are natural structures adapted for burial and funeral ceremonies of the Huns. Scythians, Sauromatae and other tribes living before the Common Era. The present-day plains and even deserts of the Eurasian continent during the Holocene and much earlier (three million years ago and before) were frozen in-depth time and again, and then thawed out in warming spells to freeze anew in follow-up cold snaps; major knolls of bulging sprung up there over many years on the site of dry thermokarst lakes. On plains they rose as burnished hills hundreds and thousands of years old to become hearths of life.

Most of the burial kurgans must have been created by Mother Nature after all. If so, such cryogenic structures are not lone phenomena but rather an ordinary feature of all cold regions of Eurasia and America.

WHEN WAS THE PATOM CRATER BORN?

Vadim Kolpakov, the Patom crater discoverer, has assessed the crater's age at 50 to 200 years. Yet a field party of the Siberian Commission on Meteorites and Cosmic Dust that analyzed sawn-off tree chunks in 1963 cites different figures: the Patom crater is supposed to be at least 250 to 300 years old. In 2006 Viktor Voronin, a dendrolo-gist, added yet another 100-150 years. Today the conclusive evidence is that the Patom crater took body and form 450 to 500 years ago. But is this native structure as young as that?

The mound is covered with large scattered fragments of limestone, crystalline schist and sandstone. Here and there we can see large disjointed blocks coming apart right there, before our very eyes. Some fragments that were whole shortly before could be joined together again. No evidence of any dug-out pits nearby, except one, 1.8 m deep, east of the cone's base. The upper bound of permafrost is visible in the face of the pit, with a dead tree amidst crushed rock. The pit is water-filled, and one was unable to go deeper. No evidence of attempts at drilling into the cone.

As observed by Zinaida Krotova and Yuri Kandyba, two researchers from the town of Novokuznetsk who took part in the 1961 expedition, some of the crescent-shaped bank of the crater is overgrown with vegetation (larch, fir, bushes, lichen). They believed the trees to be no more than 100 years old. No trace of the erstwhile forest edge! Nobody could tell where it was gone. The latest photos show just single trees, while the cone surface looked like a typical "curum" (rock stream)--versant cryogenic deposits of common occurrence in the holz belt of the mountains of Siberia, Chukotsk, the Urals and other regions of the cryolithozone. The lower part of curums is usually under slowly fragmenting fractions of loose rock, down to gruss (landwaste). Thereby the silt and humus (the most productive, life-giving part of soil) is washed off by suprapermafrost water streams beyond the cryogenic deposits. In springtime, during snow melting, the curum is ice-filled, with defrosted fragments moving off, and the ice-and-ground mass sliding down the slope. That is why the curums are bare of vegetation cover.

Under natural conditions curum formation proceeds most vigorously during cold spells, and it is starkly manifest in the modern climatic phase--it all depends on rock composition and hydrothermal conditions of cryohyper-genesis (supercold). It is hard to determine the age of curums since they are covered all over by mountain masses of different age and composition, from the Archean to Quaternary volcanic associations.

In keeping with the Dr. Sergei Fotiev (Institute of Cryosphere of the Earth, RAS Siberian Branch) ge-ocryological chronicle, curums could have appeared in the Late Cenozoic (3.1-0.0 mln years ago), which means the Patom cone could have come up anytime during this period and continued in existence for thousands of years. In fact, the age of some hydrolaccolites on North America's coast is estimated in the range of 4 to 7 thousand years, their formative process dragging on for thousands of years. Carbon radiography of the peat coating 17 m bulgunnyakh mounds in the Evoyakh river valley in the north of the West Siberian Plain shows: the mound started growing 5,000 years ago, and kept bulging at an annual rate of 2 to 3 centimeters (an inch or so) for as long as 2,500 years. However, a complex of hydrogeologi-cal, geothermal, geophysical and other investigations is needed to clinch the matter of the Patom crater and of its origin and formative time.


© libmonster.ru

Permanent link to this publication:

https://libmonster.ru/m/articles/view/THE-RIDDLE-OF-THE-PATOM-CRATER

Similar publications: LRussia LWorld Y G


Publisher:

Россия ОнлайнContacts and other materials (articles, photo, files etc)

Author's official page at Libmonster: https://libmonster.ru/Libmonster

Find other author's materials at: Libmonster (all the World)GoogleYandex

Permanent link for scientific papers (for citations):

Vladimir ALEXEYEV, THE RIDDLE OF THE PATOM CRATER // Moscow: Russian Libmonster (LIBMONSTER.RU). Updated: 20.11.2021. URL: https://libmonster.ru/m/articles/view/THE-RIDDLE-OF-THE-PATOM-CRATER (date of access: 04.12.2021).

Found source (search robot):


Publication author(s) - Vladimir ALEXEYEV:

Vladimir ALEXEYEV → other publications, search: Libmonster RussiaLibmonster WorldGoogleYandex


Comments:



Reviews of professional authors
Order by: 
Per page: 
 
  • There are no comments yet
Related topics
Publisher
Россия Онлайн
Москва, Russia
57 views rating
20.11.2021 (13 days ago)
0 subscribers
Rating
0 votes
Related Articles
THE BLACK-SEA ORIENTATION: PAST & PRESENT
Yesterday · From Россия Онлайн
NOT BY THE BLACK SEA ALONE RELATED
Yesterday · From Россия Онлайн
Праздник молодежи на Поклонной горе
Yesterday · From Россия Онлайн
Из первых рук. Помогает военнослужащим получить гражданскую профессию Российско-Британская программа
Yesterday · From Россия Онлайн
ГРЫЗТЬ ГРАНИТ НАУКИ ПОМОГУТ ГРАНТЫ
Yesterday · From Россия Онлайн
Солдат, коннозаводчик, поэт и переводчик
Yesterday · From Россия Онлайн
Переводчик в России - больше, чем переводчик
Yesterday · From Россия Онлайн
ПРИОБРЕТАЯ ОДЕЖДУ, БУДЬТЕ БДИТЕЛЬНЫ
Catalog: Экономика 
Yesterday · From Россия Онлайн
«Мозг каждого может измениться». Как об этом позаботиться?
Catalog: Логика 
Yesterday · From Россия Онлайн
Физика заблудилось меж двух сосен Анонс Изучение новой теории электричества, пожалуй нужно начинать с анекдота, которой актуален до сих пор. Профессор задаёт вопрос студенту: что такое электрический ток? Студент: я знал, но забыл. Профессор: какая потеря для человечества, никто не знает, что такое электрический ток, один человек знал, и тот забыл. После того, как Фарадей открыл индукционный ток, физика озадачила учёных вопросом, что такой электрический ток. Вразумительного ответа по сей день нет.
Catalog: Физика 

Actual publications:

Latest ARTICLES:

Libmonster is the largest world open library, repository of author's heritage and archive

Register & start to create your original collection of articles, books, research, biographies, photographs, files. It's convenient and free. Click here to register as an author. Share with the world your works!
THE RIDDLE OF THE PATOM CRATER
 

Contacts
Watch out for new publications: News only: Chat for Authors:

About · News · For Advertisers · Donate to Libmonster

Russian Libmonster ® All rights reserved.
2014-2021, LIBMONSTER.RU is a part of Libmonster, international library network (open map)
Keeping the heritage of Russia


LIBMONSTER NETWORK ONE WORLD - ONE LIBRARY

US-Great Britain Sweden Serbia
Russia Belarus Ukraine Kazakhstan Moldova Tajikistan Estonia Russia-2 Belarus-2

Create and store your author's collection at Libmonster: articles, books, studies. Libmonster will spread your heritage all over the world (through a network of branches, partner libraries, search engines, social networks). You will be able to share a link to your profile with colleagues, students, readers and other interested parties, in order to acquaint them with your copyright heritage. After registration at your disposal - more than 100 tools for creating your own author's collection. It is free: it was, it is and always will be.

Download app for smartphones