Continents Archives - GeoCurrents

A Semi-Serious Historically Based Alternative World Regionalization Model

Article-Grid, Continents / Martin W. Lewis

As I argued in the previous Geo-Currents post, the semi-standard world regional model is indispensable for understanding global geography. But as it is also highly flawed, it should be complemented with other models. I have therefore devised an alternative scheme, one designed to more accurately reflected deep cultural affinities. It is highly idiosyncratic and problematic in its own right, and is offered partly in jest. I certainly don’t expect anyone to use it. But my rationale for mapping the world this way might be of some interest to others.

My first maneuver is to detach Australia and New Zealand from Oceania and group instead them with the United States and Canada. Doing so creates a disconcertingly discontinuous region, but its sub-units are at least separated by water rather than land. The historical and cultural affinities of these four countries are obvious and need no explanation. Greenland does fit on such grounds, but its main cultural and historical connection are with the Inuit zone that extends across northern Canada and northern Alaska.

I have also separated the islands of the Caribbean, as well as the mainland polities of Guyana, Suriname, French Guiana, and Belize, from Latin America and placed them in their own Caribbean region. This maneuver is fairly common and is even found in some supposedly continental maps. It is also encountered in a few college textbooks, including one that I co-authored.

Extracting Madagascar and the other insular polities of the southwestern Indian Ocean from Africa and placing them in a small world region of their own is, as far as I know, an unprecedented move. I have labeled this region “Indo-Africa” in reference to its dual Indonesian-African (Madagascar) and Indian-African (the Mascarene Islands) cultural heritage.

Although the Horn of Africa is conventionally designated as an African or sub-Saharan African sub-region, I have never seen it specified as a world region. I have idiosyncratically mapped it in such a manner to highlight the deep cultural and historical divergence separating the highlands of Ethiopia and Eritrea from the rest of sub-Saharan Africa. Sub-Saharan Africa is also arguably too large and diverse to be mapped as a single world region. I have included Somalia and Djibouti in this region largely to indicate their deep heritage of interactions within the Indian Ocean maritime area. In a world-regional model that allows the division of countries, I would consider placing coastal Kenya and Tanzania – and especially Zanzibar – in the same region. But these areas also have close connections with other parts of Africa, showing the usefulness of retaining multiple world-regional models.

I have also divided the large world region of North Africa and Southwest Asia on cultural and historical grounds, dubbing its southwestern portion “MacroArabia.” Most of this putative region is linked together by Modern Standard Arabic, used an official language across almost the entire region. Israel is an exception, although it did count Arabic as an official language until 2018. Admittedly, Israel does not fit particularly well into this region and should perhaps be regarded as unclassifiable in this scheme.

I have grouped the rest of Southwest Asia and North Africa – Turkey and Iran – with Central Asia and Caucasus to form a region awkwardly dubbed “Turko-Persia.” Here I follow the lead of the anthropologist Robert Canfield, who outlined a similar region in his edited collection, Turko-Persia in Historical Context. Turkic and Persian peoples have a long and intense history of cultural interaction, and all the countries that I have placed in this region, except Georgia and Armenia, have either a Turkic tongue or Persian as their main language (provided Dari is given precedence over Pashto in Afghanistan). Georgia and Armenia do not fit nearly so well, but their early-modern history is deeply entangled in the Turkic and Persian realms.

At the risk of offending most Ukrainians, I have placed Ukraine in the same region as Russia and Belarus. All three countries trace their political histories back to the eastern Slavic state know as Rus, and their cultural connections are profound.

I have taken Vietnam out of Southeast Asia and placed it East Asia for reasons specified in the previous post: a legacy of Confucianism, Mahayana Buddhism, an originally Chinese-based writing system, traditional Chinese-derived ideas of statecraft, and a history of intellectual exchange across the so-called Sinosphere. What remains of Southeast Asia are countries that were originally rooted in Indian-derived cosmological and political ideas,* but whose unity was later sundered by the spread of new universalizing faiths (Theravada Buddhism in Burma, Thailand, Cambodia, and Laos; Islam in Malaysia, Brunei, and Indonesia; and Christianity in the Philippines and East Timor). In a model in which countries can be divided, Eastern Indonesia would be extracted from this region and grouped instead with Oceania.

Mongolia occupies an uncertain position in this alternative model. If countries could be divided, it would group best with the Russian republics of Buryatia and Kalmykia (as the Mongolic-speaking realm), and with the greater Tibetan Plateau of China (as the region of Tibetan Buddhist religious heritage). Such a region, however, although would be discontinuous. In the textbook that I co-wrote, Mongolia is placed in Central Asia, along with western China, which we placed both in East Asia and Central Asia. Mongolia does fit well in a Central Asian world region, but it is a poor match for the more limited region that I have dubbed “Turko-Persia.” As a result, I have labeled it here, with frustration, as “unclassified.”

*The Philippines is usually excluded from the early-historical Indic realm of Southeast Asia, but early Indian influence across the archipelago was nonetheless profound.

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Problematic Countries in the World Regional Model

Article-Grid, Continents / Martin W. Lewis

While the continental model is ostensibly based on physical features, the world regional model is keyed more to geopolitical factors. As a result, it does not generally divide countries among regions. The one exception is France, whose exclaves (overseas departments) are usually placed in Latin America (Guiana, Guadeloupe, and Martinique) and sub-Saharan Africa (Réunion and Mayotte). I have mapped them accordingly (see the map re-posted below). Overseas dependencies, however, are usually separated from the state that holds sovereignty over them. As a result, I have mapped Puerto Rico not with the United States in North America but rather as part of Latin America. For the same reason, I have placed Guam and the Northern Mariana Islands in “Australia and Oceania.”

The world regional model also differs from that of continents in the larger number of countries that occupy an uncertain position, which I have specified on a map (re-posted below). The ambiguous status of these countries needs clarification, which is provided in the remainer of this post. As the most problematic cases are found in the former Soviet Union, I begin there.

Map of Uncertain Countries in the World-Region Model

The world regional model emerged in the Cold War period, when the Soviet Union and its Warsaw-Pact satellites seemed to form a stable region, based largely on geopolitical criteria. When the Soviet system unexpectedly collapsed, a substantial degree of re-regionalization was necessary. Eastern Europe, including the former-Soviet Baltic states, was easily slotting into Europe based on historical and cultural factors, as well as the eastward expansion of the EU and NATO. Russia understandably came to form the core of its own world region, but the position of most of the other post-Soviet states remained uncertain. In most schemes, a new world region called Central Asia appeared on the map, focused on the five former-Soviet “‘stans” (Kazakhstan, Kyrgyzstan, Tajikistan, Uzbekistan, and Turkmenistan). Central Asia has solid historical and cultural grounding, although its extent remains contested. I have included Afghanistan in it, although this country can just as easily be placed in South Asia or in Southwest Asia & North Africa. More controversial are the three countries of the Caucasus: Georgia, Armenia, and Azerbaijan. As most Georgians and Armenians strongly prefer to be grouped with Europe, I have mapped them accordingly, although this maneuver remains unconventional. In contrast, I have placed Azerbaijan in Central Asia, due to cultural, historical, and economic consideration; such mapping, however, sunders the unity of trans-Caucasia. Ukraine is equally problematic. If cultural and historical factors are given precedence, Ukraine clearly belongs with Russia and Belarus. Most Ukrainians, however, favor affiliation with Europe, although it is a different story with the Russian-speakers of Crimea and the Donbass. Any clear regionalization of this area will have to wait until the end of the current conflict. Finally, I have placed Moldova in Europe due to its extremely close cultural and historical connections with Romania, although the de-facto independent statelet of Transnistria along its eastern flank is a different matter.

Turning to the Western Hemisphere, I have indicated an uncertain position for all the Caribbean, including the mainland polities of Guyana, Suriname, French Guiana, and Belize. In some schemes, this area constitutes its own world region. Its English-speaking countries, such as Jamaica, Guyana, and Belize, do not culturally fit in “Latin America,” which is defined by its official Romance (Latin-based) languages. But even French- and Creole-speaking Caribbean lands are a poor fit, as Latin America is historically linked to the experience of Iberian (Spanish and Portuguese) colonization. Although it is awkward to exclude Spanish-speaking Caribbean polities (Cuba, the Dominican Republic, and Puerto Rico) from Latin America, it is essential to note that they also strong significant affinities with the rest of the Caribbean.

I have also indicated an uncertain status for most polities in the Pacific. These areas are conventionally grouped with Australia and New Zealand, but there is little that ties together this vast but mostly oceanic region. What, for example, do New Zealand and Papua New Guinea have in common? Australia and Oceania thus seems to largely be a world region of convenience, with little cultural and historical coherence. To be sure, the islands of Polynesia (including Hawaii) have deep cultural connections with New Zealand, but those of Melanesia do not. Australia has regarded most Melanesia as being within its sphere of influence, but it is questionable whether such claims are adequate for world-regional delineation.

The islands of the southwestern Indian Ocean are conventionally placed in sub-Saharan Africa, but the rationale for doing so is tenuous. Cultural and historical affinities link Madagascar to both Africa and Southeast Asia, but the connection to Southeast Asian is much stronger in terms of language and deep history. From what I gather, moreover, many Malagasy people object to their classification in Africa. The other island polities in the area, particularly Mauritius and Réunion, have both African and South Asian cultural connections. They seem to have been placed in sub-Saharan Africa largely for convenience.

I have mapped Vietnam as having an uncertain world-regional status even though it is unquestionably placed in Southeast Asia. In cultural-historical terms, however, Vietnam arguably fits better in East Asia. The cultural definition of East Asia rests on a legacy of Confucianism, Mahayana Buddhism, an originally Chinese-based writing system, traditional Chinese-derived ideas of statecraft, and a history of intellectual exchange across the so-called Sinosphere. By these criteria, Vietnam belongs in East Asia, although it also has important cultural, historical, and political affinities with Southeast Asia.

The definition of East Asia mentioned above would preclude placing Mongolia in the region. Mongolia could conceivably be categorized alongside Russia, but on deep cultural and historical grounds it is probably best placed in Central Asia. Doing so, however, would create a discontinuous region, although just barely.

Finally, I have marked Sudan and Mauritania as countries of uncertain world-regional designation. They are usually mapped in sub-Saharan Africa, which seem appropriate as most of their inhabitants live south of the Sahara. But despite the use of the physical-geographical term “sub-Saharan,” world regional divisions are ideally based on features of the human world. As Sudan and Mauretania are predominantly Arabic-speaking countries, it seems fitting to place them in the same region as the other Arabic-speaking countries (North Africa and Southwest Asia).

In the final analysis, the semi-conventional world regional model that I have mapped is a useful and even necessary device for understanding and communicating about the world. It is also a vast improvement over the continental model for organizing human-geographical knowledge. But it remains far from ideal, and as a result it needs to be constantly questioned and scrutinized. Just as important, it should be complemented with alternative regionalization schemes, some of which should be based on different criteria.

In the final Geo-Currents post in this series, I will explore a few possible but problematic revisions to the standard world regional model.

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From Continents to the World Regional Model

Article-Grid, Continents / Martin W. Lewis

Despite my harsh criticisms of the continental model expressed in the preceding posts, I do think that it should be taught to young students. In my ideal scenario, first-graders would be shown, ideally by examining a globe, that there are six very large masses of land that are separated, or almost separated, from each other by waterways. The distinction between large islands and continents should also be discussed. Students also need to be informed that Eurasia is usually divided into two continents, Europe and Asia, for largely historical reasons. Coloring in and labeling the continents on a world map could then proceed. Everyone should learn the names of these landmasses and be able to identify them on a world map or globe.

My problem with the continental model is not that it is taught, but rather that it is usually the only lesson in dividing the world, other than by countries. Problems with, and alternatives to, the continental model should be introduced in the elementary grades. The model’s flaws, after all, are obvious to anyone who pays close attention to the world, leading to a slew of unanswerable questions. Since Israel and the Palestinian territories are in Asia, why are Israelis and Palestinians not considered Asian? If Tunisia is in Africa, why is a Tunisian immigrant to the United States not an African American? Why is there no appreciable significance to the division of Turkey and Russia between Europe and Asia? Such paradoxes go on and on.

The main alternative to the continental model is that of world regions (see the map posted below), which has been used by serious thinkers since the end of World War II. This model is not as formalized as the continental scheme, with more countries occupying uncertain or contested positions (see the second map below). It aims to divide the world not on a geological basis but rather in accordance with historical and cultural factors. The resulting model has many problems and controversies, and should never be taken-for-granted, much less regarded as definitive. But it is indispensable for anyone wanting to discuss world geography effectively.

Countries with an Uncertain Position in the World Regional Model

Unfortunately, the world regional model is almost never taught at the elementary or secondary levels, at least in the United States. Even at the tertiary level, it is rarely introduced outside of a few geography courses, which are absent at many if not most colleges and universities. Beyond academic discourse, the outlines of world regionalization remain poorly known and deeply confused. Consider, for example, the top results of a Google image search for “world regions map,” which are posted below. Few of the maps in this illustration depict the standard world regions of the scholarly imagination.

Even many professors working on global topics have little understanding of the world regional model that guides global scholarship. Some are evidently determined to remain ignorant. I once gently corrected a professor of economics who kept referring to Singapore, Malaysia, and the Philippines as “East Asian” countries, informing him that they are in Southeast Asia, not East Asia. He was infuriated, screaming back that “In the discipline of economics, the Philippines is in East Asia!” I have found no evidence that this assertion is true, and, even if it were, economists have no warrant to idiosyncratically divide the world as they see fit. Suffice it to say that a scholar of the Philippines is never going to be considered for an academic position in East Asian studies or East Asian history.

The map posted above of “Countries & Dependencies With an Uncertain or Disputed World-Regional Position” needs explication, which will be given in the next GeoCurrents post.

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Adding New “Continents” to the Map of the World – and thus Approaching the World-Regional Model

Article-Grid, Continents / Martin W. Lewis

Almost all maps found in online image searches of “continents map” depict the standard seven-continent model of the U.S. educational establishment. A few, however, deviate from the scheme by adding additional continents. Such adjustments are understandable, as the standard model does little to help us understand the world. But merely adding a continent or two does not solve the underlying problem. An alternative model is needed, as will be explored in a later post. For now, I will consider a few maps posted online that divide the world into more then seven major landmasses.

Let us begin with a map produced by a storied publication, one that I have treasured for decades: Encyclopedia Britannica. The elementary Brittanica map posted below only slightly deviates from the standard model, adding an additional landmass between North and South America. Or is it two? The coloration scheme suggests one, but the labeling indicates two: Central America and the Caribbean. Either way, this continent (or continents), is (or are) way out-of-scale with all others. Such mapping, moreover, has little if any justification in terms of geology, biogeography, human culture, or anything else. It also defines the convention used elsewhere on the map by setting continental boundaries along geopolitical rather than physical features. The only rationale that I can imagine for putting Mexico in one continent and Guatemala in another is the economic organization formerly known as NAFTA.

The World Atlas map posted below essentially makes the same maneuver, although it does specify that Central America and the Caribbean are to be construed as separate entities. More important, it adds the “Middle East” as a tenth division of the world. But this is not the Middle East as it is conventionally defined (see the second map posted below). Egypt is excluded while Pakistan and much of Central Asia are included. The northeastern boundary of this “Middle East,” moreover, is inexplicable, as it does not correspond to geopolitical boundaries – or any other divisions that I am aware of. More bizarre is its depiction of the Black Sea as part of Europe. Other curious features include a gap between Central and South America, a significant westward displacement of South America, the deletion of Tierra del Fuego, the magnification of the Falkland/Malvinas islands (perhaps this is a misplaced Tierra del Fuego?), and the skewing of the boundary between Indonesia and Papua New Guinea. Simple cartographic incompetence seems to be as much of a problem here as conceptual confusion.

At first glance, the Nations Online map posted below seems to depict both the Middle East (minus most of Egypt) and Central Asia as separate continents. The caption, however, indicates that they are to be regarded as “continental subdivisions.” But to which continent do they belong? The color scheme, not surprisingly, suggests Asia, but no specification is made. The only other “continental subdivision” mapped through color is Greenland, and its hue is roughly halfway between that of North America and that of Europe. Is the viewer supposed to guess which continent it belongs to? This map also indicates that Central America and the Caribbean together form a subcontinent of South America, an idiosyncratic classification. It also has a subcontinental label for “Middle America,” which is evidently intended to denote Mexico, even though part of it sits over Cuba. Such mapping defies conventional regionalization, in which “Middle America” groups together Mexico, Central America, and the Caribbean as a subdivision of North America (see the second map posted below).

The Reddit map posted below, depicting a ten-unit scheme of “comparable ‘continents’” is the most admirable of the lot. Here the cartographer is seriously grabbling with the problems inherent in the continental division of the world. But the map has strayed so far from the standard model that the term “continent” loses all meaning. What this map depicts, at least in the Eastern Hemisphere, are not “continents” but rather “world regions.” The world regional model is indeed the appropriate replacement for the continental model for general educational purposes. It has been used as such by scholars and other informed writers since the middle of the twentieth century. It is beyond time to introduce it into the elementary-school curriculum, although the chance of that happening any time soon is close to nil.

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The Problem of Mapping Transcontinental Countries

Article-Grid, Continents / Martin W. Lewis

As noted in the previous post, most maps of continents found in online images searches divide several countries, particularly Russia and Turkey, along conventional continental lines yet avoid dividing Indonesia in the same manner. Evidently, in the popular cartographic imagination, geopolitical factors override geophysical factors in the delineation of continents in some instances but not in others. A few maps, however, consistently follow political divisions in delineating continents, just as a few consistently follow features of physical geography.

Cartographers who map continents along political borders must use judgement when slotting countries that are conventionally regarded as transcontinental. In general, this is a minor issue. In conventional reckoning, there are only a few transcontinental countries, although the list grows considerably longer if one if one includes dependencies and territorial claims within a given country’s boundaries and regards “Oceania” as a continent (compare the two maps posted below). More to the point, in all cases but one a substantial majority of both the territory and population of transcontinental countries are situated on one continent. I do not know any map, for example, that puts Egypt in Asia rather Africa because the Sinai Peninsula is on the Asian side of the continental divide. Some maps do, however, place Turkey in Europe rather than Asia regardless of its territorial and population imbalance. They presumably do so largely because of Turkey’s stalled application to join the European Union.

Russia is the one country with a questionable position in a classification scheme that does not allow countries to be continentally divided. Most the territory of the Russian Federation is technically in Asia, as it is east of the Ural Mountains, whereas most of its people live in its “European” heartland. Some geopolitically based continental maps thus put Russia in Asia while others put it in Europe. Both depictions have problems. Extending “Europe” to the Pacific Ocean, as can be seen on the DataBayou map posted below, makes the “continent” all but unrecognizable. Slotting European Russia into Asia, as is done in the WorldAtlas map posted below, requires the addition of an Asian exclave (Kaliningrad) on the Baltic Sea between Poland and Lithuania, which is also visually jarring.

The cartographers who made this WorldAtlas map could have ignored Kaliningrad’s geopolitical status and mapped it as part of Europe, thereby retaining clean continental borders. They mapped France’s exclaves – Guiana, Martinique, Guadeloupe, Réunion, and Mayotte – after all, as belonging to South America and Africa rather than Europe. In these cases, in other worlds, they ignored the geopolitical standard that they used elsewhere when partitioning the continents. Note as well their mapping of Hawaii, which they misplaced, in North America and of Greenland in Europe. Their depiction of Central America and the Caribbean as parts of South America rather than North America also defies conventional continental categorization. Yet again we find ourselves in a conceptual morass.

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The Conceptual Incoherence of the Standard Continental Model

Article-Grid, Continents / Martin W. Lewis

The division of the terrestrial world into seven continents is seemingly the simplest topic in geography, yet it is actually one of the most complex – which is precisely why I find it so fascinating. Unfortunately, the educational establishment grasps only its superficial simplicity, ignoring the more important and interesting issues involved. The result, to put it bluntly, is miseducation of the young.

It is not difficult to demonstrate the poverty of the continental model. If a group of bright but geographically unschooled students are given a globe or an equal-area-projection map of the world and asked to count the planet’s major masses of land, they would never list the seven continents of the standard scheme, as there is nothing even approaching a physical separation between Europe and Asia. As a result, teachers generally explain that Europe and Asia, unlike the other continents, are regarded as if they were distinct landmasses because of features associated with humankind rather than with the natural world. Such an explanation, however, is misleading and largely incorrect. There is almost nothing in human history, culture, politics, economics, or demographics that separate European Russia from Asiatic Russia, European Turkey from Asiatic Turkey, or European Kazakhstan from Asiatic Kazakhstan. These countries are instead conventionally divided between the two continents on the basis of disputed minor physical features: the Ural Mountains, the Ural River, and the Turkish Straits. Yet none of these features are, or have ever been, significant barriers to movement, either of people or of other species. As a result, they make poor continental boundaries.

Conventional Borders Between Europe and Asia Map

Various Boundaries Between Europe and Asia Map

The separation between Europe and Asia – the original continental divide, around which all others were conceptualized – is thus rooted in physical geography despite the absence of physical separation. But elsewhere in the world, it is a different story. As a simple image search of “continents map” reveals, a substantial majority of such maps terminate Asia along an almost entirely straight north/south line slicing across the middle of New Guinea, with the eastern half of this vast island appended instead to Australia. In a geologically informed understanding of continents, all New Guinea belongs with Australia. But in the simplistic pedagogical understanding, the political division of the island between Indonesia and Papua New Guinea, based on a colonial agreement between the U.K, the Netherlands, and Germany, overrides all geological, biogeographical, cultural, and deep-historical considerations. Evidently, since Indonesia is defined as an Asian country, all its territory gets slotted into Asia, regardless of whether it makes any sense to do so.

Maps of the Continents with New Guinea Divided

But if geopolitical considerations are used to delimit the southeastern extremity of Asia, why are they not employed in the west, where several countries are split between Europe and Asia (Russia, Turkey, Kazakhstan, and even Georgia) and Asia and Africa (Egypt)? Or, to reduce the argument to absurdity, why is French Guiana – as much a part of France as Alaska is part of the United States – mapped as part of South America rather than as part of Europe with the core of the French Republic? The answer is simple: because continents are physical entities that have nothing to do with political boundaries – except, that is, when they do, as in the case of New Guinea.

What we have here is conceptual mess of the first order. Yet this is how we begin teaching world geography to elementary-age children. And in the United States, it often seems that we go little beyond that. Is it any wonder that the geographical ignorance of the average American student has become an object of both shame and amusement? It should be regarded as a national scandal, evidence of an unconscionable failure to teach basic world geography.

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How Does an Updated Map of Zoogeographic Regions Mesh with the Architecture of Continents?

Article-Grid, Continents, Physical Geography / Martin W. Lewis

An important 2013 article in published in Science, “An Update of Wallace’s Zoogeographic Regions of the World,” redivides the world’s faunal regions. The study is based on a sophisticated statistical and phylogenetic analysis of 21,037 species of amphibians, non-pelagic birds and terrestrial mammals. In the end, the authors split the world into 11 zoogeographic realms, almost twice as many as Alfred Russel Wallace demarcated in 1876. They also subdivide some of these “realms” into smaller zoogeographical “regions,” resulting in 20 separate divisions. (See the three maps posted below.)

Alfred Russel Wallace’s Zoogeographic Regions Map

These updated zoogeographic maps stray further from the continental architecture than Wallace’s map of 1876. Let us begin with the first map, which depicts the larger faunal “realms.” Here the Eurasian Palearctic zone extends across most of the tundra zone of far northern North America, reflecting linkages that were established during glacial periods when the sea level was lower than it is today. But in the Eastern Hemisphere, the Palearctic zone is more restricted than it is in Wallace’s scheme, as North Africa and most the Middle East are placed instead in a separate Saharo-Arabian realm, while Japan, Tibet, and eastern China are also given a realm of their own. The new map retains Wallace’s “Oriental” faunal zone in South and Southeast Asia, but pushes its boundary farther to the southeast, reaching the zoogeographic line of Weber rather than that of Wallace. New Guinea is removed from Australia and appended instead to an “Oceanian” realm, while New Zealand is linked to Australia. Finally, Madagascar is separated from Africa and placed in its own “Madagascaran” realm. All told, these revisions further differentiate the zoogeographic map from that of the continents.

The more finely divided second map deviates further still from the continental model. Here North America is split into four pieces, although the division between the Panamanian and Amazonian regions does come close to the continental border between North and South America. Both South America and Sub-Saharan Africa are divided into two faunal regions. More important, Eurasia vanishes entirely, split among no fewer than eight zoogeographical regions. Intriguingly, the separation of the Indo-Malayan region from the larger Oriental realm almost exactly follows the conventional geographical division of Southeast Asia into Mainland and Insular (island) sub-regions. Note also the “Papua-Melanesian” outliers in northeastern Australia.

It is not surprising that these new maps place Madagascar in its own faunal realm and region. Although Wallace had slotted Madagascar, along with the Mascarene Islands and Seychelles, in a distinctive faunal subregion, he still placed it within thhise larger “Ethiopian” region (Sub-Saharan Africa, essentially). I have always found this classification perplexing, as the fauna of Madagascar is very distinctive. The landmass containing Madagascar, India, and Seychelles rifted away from Africa some 130-160 million years ago, while Madagascar began to split from India around 85 million years ago. As a result of this long separation, Madagascar developed its own faunal assemblage. As another map in the “Update of Wallace’s Zoogeography” article reveals (posted below), Madagascar has the second highest level of “evolutionary uniqueness” among the world’s zoogeographical regions, following only Australia. Such uniqueness is especially pronounced among mammals. As described in a Wikipedia article:

The mammalian fauna of Madagascar is highly distinctive and largely endemic. The extant nonmarine, nonchiropteran [non-bat] taxa constitute (as of June 2014) 168 species, 40 genera and 9 families; of these, besides a probably introduced shrew, endemic taxa make up all the species, all the genera, and all but one of the families. This endemic terrestrial fauna, consisting of lemurs, tenrecs, nesomyine rodents and euplerid carnivorans, is thought to have colonized the island from Africa via four (or five, if aye-ayes arrived separately) rafting events. The other historic terrestrial or semiterrestrial mammal group, the extinct hippopotamuses, is thought to have colonized the island possibly several times, perhaps via swimming

The fauna of Madagascar, moreover, had been far more distinctive than it is today prior to the initial human settlement of the island roughly 2000 years ago. As the Wikipedia article cited above also notes:

Earlier in the Holocene, Madagascar had a number of megafaunal mammals: giant lemurs such as Archaeoindris which at over 200 kg was comparable in mass to the largest gorillas, as well as the hippopotamuses. The island also hosted flightless elephant birds weighing up to 700 kg, the largest known birds of all time. All of these went extinct following the first appearance of humans about 2000 years ago. Today, the largest surviving native mammals of the island, such as the indri and fossa, have weights only approaching 10 kg. Most if not all of the 29 listed extinct species are believed to have died out in prehistoric times; none of these are known to have survived into the post-European contact period.

As a final comment, the “Update of Wallace’s Zoogeographic Regions” article includes separate maps of amphibian, avian, and mammalian regions. Intriguingly, North America (minus the Caribbean) forms its own amphibian region, as do Madagascar, New Guinea, and the Philippines. It is probably not coincidental that North America, and especially the southeastern United States, has by far the world’s greatest salamander diversity (see the map below). The map of mammalian regions is also noteworthy, as it is here that the relationship between continents and zoogeographical regions collapses most completely.

Amphibian, Bird, & Mammal Zoogeographic Regions map

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Zoogeographical Regions & the Architecture of Continents: The Legacy of Alfred Russel Wallace

Article-Grid, Continents, Physical Geography / Martin W. Lewis

If the division of the terrestrial world into continents is partially but misleadingly rooted in geology, as recent GeoCurrents posts have argued, we must also ask whether it reflects the distribution of animal and plant life. Are continents, in other words, entities of biological significance? To answer this question, it is useful to begin with the work of Alfred Russel Wallace (1823–1913), the “father of zoogeography.” Wallace was one of the world’s greatest naturalists, deserving far greater recognition than he receives. Most impressively, he derived the theory of evolution through natural selection independently from Charles Darwin. Indeed, Darwin only decided to publish The Origin of Species after he received a letter from Wallace that outlined the same key ideas.

Wallace is probably best remembered for his pioneering work in biogeography. The line that he drew separating the fauna of Southeastern Asia from that of Australia – Wallace’s Line – still appears on many maps, although it was later repositioned by other authorities (see the map below). Wallace’s interest in zoogeography was of global scope, as reflected by this two-volume study The Geographical Distribution of Animals: With a Study of the Relations of Living and Extinct Faunas as Elucidating the Past Changes of the Earth’s Surface, first published 1876.

In this work, Wallace distinguished six great zoogeographical regions, or faunal realms, which he subdivided into smaller units. Slightly modified maps of Wallace’s scheme are still commonly encountered, remaining a cornerstone of zoogeography. To be sure, other authors have devised their own regionalization systems, one of which will be examined in a forthcoming post. But it still behooves us to compare Wallace’s pioneering map with the familiar depiction of continents to see the extent to which they coincide.

Alfred Russel Wallace’s Zoogeographical Regions Map

Map of Zoogeographical Regions Based on Wallace

The simple answer is that Wallace’s scheme accords reasonably well with the standard six-continent model – which combines Europe and Asia to form Eurasia – but with a few important off-sets and one significant addition. Wallace’s Nearctic region focused on North America, for example, is distinct from his Neotropical region focused on South America. The division is not at the continental boundary along the Isthmus of Panama, however, but is rather located well within North America, at the highland/lowland transition zone in southern and central Mexico. Similarly, Wallace’s “Ethiopian” region includes southern Arabia but excludes the part of Africa located north of the Sahara, which is instead appended to the Eurasian Palearctic region. The barrier separating these two faunal regions is thus one of aridity rather that one of water. Eurasia is itself divided, with the Indian subcontinent, along with most of Southeast Asia and southern China, forming its own “Oriental” region. Here the division is both topographic, marked by the Himalayas and other imposing highlands, and climatic, with the tropics separated from the temperate zone. Wallace’s scheme also extends the Australian zoogeographical region well beyond the continent of Australia. Not surprisingly, it includes New Guinea, which sits on the same chunk of continental crust. But it also encompasses New Zealand, which is part of the mostly submerged continent of Zealandia, as well as eastern Indonesia and the larger archipelagos of Melanesia. To sum it up, one might say that Wallacian zoogeography is partially but imperfectly lodged in the architecture of continents.

For most of the Cenozoic Era (the “age of mammals,” 66 million years ago to the present), the linkage between continental landmasses and distinct faunal assemblages was closer than it is today. South America, most notably, had been an isolated “island” with a unique set of animals for millions of years. It started to rift away from Africa some 130 to 110 million years ago, during the Cretaceous period, and did not gain a connection to North America until roughly 2.7 million years ago. The subsequent linkage of the two American landmasses resulted in the “Great American Biotic Interchange” (or GABI). In this exchange, many South American species moved north just as many North American species moved south. The result was a degree of homogenization of the faunas of the two continents. The main zoological division also moved north into southern Mexico, as it came to be based more on climate than on the legacy of physical separation.

South America as an Island 60 Million Years Ago Map

As is mentioned above, several studies have devised their own schemes of zoological regions, most of which remain relatively close to that of Wallace. One of the most detailed of these revisions is found in a 2013 article modestly entitled “An Update of Wallace’s Zoogeographic Regions of the World.” As we shall see in the next GeoCurrents post, the maps in this impressive article depict a much more intricate situation, as well as one that strays further from the continental model.

Zoogeographical Regions & the Architecture of Continents: The Legacy of Alfred Russel Wallace Read More »

The Biological Significance of Micro-Continents: The Fascinating Caecilians of Seychelles (and Other Parts of the World)

Article-Grid, Continents, Physical Geography / Martin W. Lewis

On the surface, there is little to distinguish small islands on continental fragments from oceanic islands that have no continental connections. Careful observation, however, can reveal some interesting differences. The Seychelles microcontinent in the Indian Ocean is an intriguing case in point. The islands sitting on this chunk of continental crust constitute a sovereign state, also called Seychelles. Seychelles is a small country of only 176 square miles (457 km²) spread out over 115 islands, fewer than a dozen of which are inhabited. Roughly 90 percent of its 118,000 inhabitants live on Mahé, the largest island in the archipelago, which is only 60.7 square miles in extent. A relatively prosperous country – with the highest per capita GDP in Africa, the continent to which it is conventionally appended – Seychelles relies heavily on tourism, much of which is up-scale.

I doubt that many tourists notice anything distinctive about the physical geography of Seychelles. To be sure, its mountainous main islands are nothing like the low coral atolls of the Maldives, another tourism-dependent Indian Ocean country. But they might seem reminiscent of the volcanic high islands of the Pacific, such as Tahiti or those of the Hawaiian archipelago. But a geologically knowledgeable traveler would note the exposed granite of the larger Seychelles islands, which are very different from the volcanic rocks found in elevated oceanic islands. Granite erodes in a different manner than volcanic rocks, often giving rise to distinctive landscapes (see the illustration below).

The Seychelles’ granite core is old, having formed during Precambrian times roughly 750 million years ago. The area in which they formed was then part of the supercontinent of Gondwana. A large segment of Gondwana, which included Australia, Antarctica, India, Madagascar, and the Seychelles, began to rift away from the landmass roughly 145 million years ago. Madagascar-Seychelles-India later separated from Australia-Antarctica, and, later still, Madagascar broke away from this landmass. The Seychelles micro-continent finally began to rift away from India around 66 million years ago, roughly the time the dinosaurs died out and the Earth transitioned from the Mesozoic to the Cenozoic era.

As an isolated microcontinent that separated from larger land masses many millions of years ago, Seychelles has no indigenous land mammals. It does, however, have several amphibians and reptiles whose ancestors were present before it split away from the larger lands. Of these, the most interesting to my mind are eight species of caecilians, all of which are endemic to the archipelago.*

Caecilians constitute one of the three living orders of amphibians, the Gymnophiona (the others are the frogs & toads [Anura] and salamanders [Urodela]). Caecilians are a relatively diverse lot, divided into ten extant families with 44 genera and 215 species. They can be quite abundant, with hundreds or even thousands of individuals living per hectare in undisturbed tropical rainforests. Although most caecilians are relatively small, Caecilia thompsoni can reach five pounds in weight and five feet in length.

But despite their abundance in certain habitats, caecilians are rarely encountered and have been relatively little studied. Although a few species are fully aquatic, most live underground in moist soil. Although they have vestigial eyes, burrowing caecilians are effectively blind and several species have a superficial resemblance to earthworms. But, like other amphibians, caecilians are vertebrates and are thus much more closely related to humans than to earthworms. Many have thick and hardened skulls, which they use to push through the soil as they hunt invertebrates. All species have teeth, which can be sharp and of fearsome appearance. Some people with whom I shared the photos posted below recoiled, viewing caecilians as the stuff of nightmares.

As the map posted below shows, caecilians live only in humid tropical zones. Their center of diversity is the Amazon Basin, with southwestern India forming a secondary center. Seychelles is also significant, with eight species and three genera. In the Americas, the range of caecilian does not extend north of southern Mexico, but individuals of the fully aquatic species Typhlonectes natans, commonly called the “rubber eel,” have recently been found in southern Florida. Presumable, they were released into the wild by people who had kept them in aquariums.

One of the most intriguing aspect of caecilians is the care that some species give to their young, a trait that is relatively unusual among amphibians. Some caecilians, belonging to at least two families, nourish their young through “maternal dermatophagy.” As explained by Wikipedia:

[They feed their] young by developing an outer layer of skin, high in fat and other nutrients, which the young peel off with modified teeth. This allows them to grow by up to 10 times their own weight in a week. The skin is consumed every three days, the time it takes for a new layer to grow, and the young have only been observed to eat it at night.

Scientists have recently discovered that some female caecilians produce a substance very similar to milk, which is also used to feed their young. Milk is produced only by mammals, although pigeons, flamingos, and male emperor penguins feed their young with a somewhat similar substance, known as “crop milk.” Oddly, the nourishing caecilian secretions seem to be more similar to those of mammals than of birds. The discovery of amphibian “nursing” is recounted in an All That’s Interesting article:

[Researchers] … noticed that ringed caecilian young kept themselves close to the mother’s cloacal opening, the rear channel that serves urinary, digestive, and reproductive purposes. “The babies’ heads were close to the female’s cloacal opening all the time,” Jared told Scientific American. “Some even put their heads inside and seemed very excited.” The team decided to compare the intestines, bladders, cloacae, and oviducts of female ringed caecilians with and without offspring. Within the mothers’ oviducts, they found large glands full of fatty acid and a sugar-rich milky substance. The makeup of this “milk” was very similar to that of mammals. Researchers noted that it likely supplemented the protein-rich skin that the babies fed on once a week. Additionally, researchers discovered that the offspring wriggled near the cloacal opening and emitted high-pitched sounds to encourage the mother to release her milk. This phenomenon could occur up to six times a day. Such begging behavior has never been observed in amphibians before.

Another other interesting but sad fact about caecilians must be mentioned. In the folklore of several regions of India, these secretive and innocuous amphibians are feared and despised, incorrectly regarded as venomous. As a result, they are often killed whenever encountered, reportedly by being doused with salt or kerosene. Ironically, in India cobras – which kill several thousand Indians every year – are generally respected and even revered, largely because of their association with Lord Shiva.

Finally, it may be instructive to compare the geographical ranges of caecilians and moles (mammals in the family Talpidae). These highly dissimilar animals occupy similar ecological niches, living underground and burrowing to pursue earthworms and other soil invertebrates. Significantly, their ranges do not seem to overlap. Moles are found in humid (or seasonally humid) temperate areas in North America, Europe, and Asia, and do not extend into the tropics. Is it possible that they have been excluded from such areas by competition with caecilians? One place where their ranges might overlap is the southeastern Himalayas. The chatbot Grok 3, however, claims that adaptation to different microhabitats prevents moles and caecilians from living in the same places within this larger region:

In northeastern India (e.g., Assam or Arunachal Pradesh), caecilians are found at lower elevations in wet, forested areas, while Talpidae moles may inhabit higher elevations in the same region’s montane zones. However, their microhabitats rarely intersect. Caecilians favor saturated, organic-rich soils or streamside environments where their moist skin and amphibian life cycle are supported. Talpidae moles, being mammals, prefer drier, looser soils for tunneling and are less dependent on constant moisture. Elevation plays a key role: caecilians are scarce above 2,000 meters due to colder temperatures, while moles thrive at these higher altitudes.

The Biological Significance of Micro-Continents: The Fascinating Caecilians of Seychelles (and Other Parts of the World) Read More »

Mapping Continents Based on Continental Crust

Article-Grid, Continents, Physical Geography / Martin W. Lewis

As the previous GeoCurrents post argued, the division of the terrestrial world into a handful of continents derives in part from the division of the Earth’s crust into tectonic plates. But there is another geological factor equally pertinent to the concept of “continent.” It refers not to individual landmasses but rather to a particular kind of crust – the outermost rocky layer of the planet – regardless of whether it extends above sea level. If continents are defined based on continental crust, an entire “continent” could conceivably be well below sea level.

As the diagram posted below show, the Earth has two kinds of crust: oceanic and continental. Oceanic crust is relatively thin and dense, rich in iron and magnesium. Less-dense continental crust, rich in aluminum silicates, is much thicker. Being light and thick, continental crust generally extends above sea level. But the continental shelves that skirt most coastlines of continents are below sea level even though they are composed of continental crust. Several isolated fragments of continual crust are almost entirely submerged. The largest of these inundated “continents” is Zealandia, which covers approximately 4.9 million km² (1.9 million sq mi). Only about seven percent of Zealandia is currently above sea level, mostly the two main islands of New Zealand and New Caledonia. Once connected to the massive southern continent of Gondwana, Zealandia began to rift away roughly 85 million years ago. As this occurred, its crust stretched and thinned, resulting in a lower elevation than the major continents.

Although oceanic crust is generally well below sea level, exceptions occur. Extensive volcanic eruptions associated with hotspots can generate exceptionally thick oceanic crust, creating sizable island. Important examples include the Hawaiian Islands, the Mascarene Islands (Reunion and Mauritius) in the Indian Ocean, and, to some extent, Iceland. Iceland is a complicated case, however, as it is essentially oceanic but does contain a few fragments of continental crust. Kerguelen, in the southern Indian Ocean, is another such “composite” island. It is associated with a hotspot and as a result is mostly covered by rock of oceanic origin. But these rocks sit above a continental fragment that rifted away from Gondwana roughly 100 million years ago. As a result, Kerguelen is depicted as a microcontinent in the map posted below.

During glacial periods, when the sea dropped due to the massive amount of water in continental ice caps, most continental shelves were above sea level. The continents were therefore larger than they are today, with a much closer correspondence between continental crust and dry land. Zealandia, however, had subsided to such a degree that even at the Last Glacial Maximum (LGM) around 20,000 years ago, only around ten percent of it extended above sea level. But that was enough to join the islands of New Zealand together, forming a significantly larger landmass than what exists today.

The Earth at Glacial Maximum 20,000 Years Ago Map

As I was not able to find an adequate map of continental crust, I made my own, which must be regarded as a crude approximation (posted above). Several difficult judgement calls were necessary, as many island chains located tectonically active areas are composed of complex mixtures of oceanic and continental crust. Most, however, are dominated by oceanic crust, and as a result do not appear on this map (examples include the Andaman and Nicobar islands and the Kuril and Aleutian archipelagos). The Ryukyu Archipelgo, on the other hand, is composed mostly of continental crust and thus appear on this map as a narrow peninsula extending south from Japan.

Needless to say, it is difficult to derive the standard seven-continent model from this map of continental crust. A six-continent model, however, can be construed, albeit one quite different from the conventional six-continent model. Its constituent elements would be North America-Eurasia, Africa, South America, Antarctica, Australia, and Zealandia.

Mapping Continents Based on Continental Crust Read More »

Map Art or Scientific Cartography?

Article-Grid, Cartography, Continents / Martin W. Lewis

Many maps, in my view, are also work of art, regardless of their creators’ intentions. Some maps, however, are explicitly made as art, and as such are not designed to convey spatial information beyond that found in the mere geographical shapes that they contain. Increasingly, it can be difficult to tell whether a given map was created as cartographic art or as a visualization of scientific information.

Consider, for example, the three figures posted below. Two are derived from images posted on the intriguing Wayne Baisey Blogspot under the heading “World Map Art Large.” The other is taken from a Wikipedia article and is based on recent scientific research. Can you tell which is which?

The middle map is in some ways the most abstract, but its title gives it away: “The New Global Tectonic Map with the Subdivision of the Continents, Oceans, and Mobile Mountain Belts in Ca. 1200 Smaller Plates.” As this map shows, the Earth is divided into many tectonic plates – vastly more than those that are portrayed on conventional tectonic maps. As the author of the Wikipedia article “List of Tectonic plates,” where the map is found, argues, “The latest studies have shown that microplates are the basic elements of which the crust is composed…” (see the quotation below). As this author further explains, referring to the map posted above [and below] and to the scientific papers on which they are based:

Minor Plates: These smaller plates are often not shown on major plate maps, as the majority of them do not comprise significant land area. … For purposes of this list, a minor plate is any plate with an area less than 20 million km² (7.7 million sq mi) but greater than 1 million km²(0.39 million sq mi).These plates are often grouped with an adjacent principal plate on a tectonic plate world map. For purposes of this list, a microplate is any plate with an area less than 1 million km². Some models identify more minor plates within current orogens (events that lead to a large structural deformation of Earth’s lithosphere like the Apulian, Explorer, Gorda, and Philippine Mobile Belt plates.The latest studies have shown that microplates are the basic elements of which the crust is composed and that the larger plates are composed of amalgamations of these, and a subdivision of ca. 1200 smaller plates has come forward.

I find this map visually striking and both scientifically and cartographically impressive. But I do think that the cartographer should have deleted the volcanos, portrayed as “yellow dots,” and placed them instead on a companion map. As it is, in areas that are rich in volcanoes the lines showing tectonic subdivisions are completely obscured (see the map detail posted below).

Detail from New Global Tectonic Map, Western North America

Needless to say, the conventional continents are not readily visible on this map. Some their coastlines, however, are apparently outlined in green as “terrane (microplate) boundaries in the continental blocks.” In actuality, however, these lines correspond to the boundaries of continental shelves, which are covered by the sea, rather than to the continents themselves. This important point will be elaborated in the next GeoCurrents post.

Map Art or Scientific Cartography? Read More »

Are Continents Rooted in Plate Tectonics?

Article-Grid, Continents, Physical Geography, Uncategorized / Martin W. Lewis

Tectonic plates are the basic building blocks of the Earth’s lithosphere, its outermost rocky layer. As these large segments of crust slowly move, landmasses and sea expanses are gradually rearranged. The current configuration of tectonic plates shows a tight connection with the architecture of continents: North America is on the North American plate; South America is on South American plate; Africa is on the African plate; Australia is on the Australian plate; and Antarctica is on the Antarctic plate. All these plates include large stretches of the sea, but they are anchored on their eponymous continents. The only exceptions are Europe and Asia, which are both located on the Eurasian plate. These correspondences indicate that the six-continent model – in which “Eurasia” supplants “Europe” and “Asia” –most closely represents the geological foundation of the Earth’s major landmasses. The six-continent model has the additional advantage of remaining faithful to the implicit definition of continents: large landmasses that are separated – or almost separated – from other large landmasses by stretches of the sea.

Relationship between Continents and Tectonic Plates Map

A closer inspection of the tectonic map, however, reveals that the connection between continents and plates is not as tight as it seems. Note that the Eurasian plate does not include either the Indian subcontinent or the Arabian Peninsula, both of which occupy their own plates. By geological criteria, these regions might be considered continents in their own right, although they obviously lack any maritime separation from Eurasia. The actual tectonic situation, however, is more complicated than that. The Indian plate, for example, is sometimes considered to be part of a much larger Indo-Australian plate, which would seemingly imply that India and Australia are part of the same “tectonic continent.” The current consensus, however, is that India and Australia were formerly on a single plate that has either split into two separate plates or is in the process of gradually splitting. In a tectonically informed view, all continents – and oceans – are but temporary entities.

Disconnections between Continents and Tectonic Plates map

Two Depictions of the Indo-Australian Plate map

Other disconnections between continents and tectonic plates are easily located. The North American Plate, for example, includes a huge part of eastern Siberia in Asia (or Eurasia), as well as northern Japan. The same plate does not, however, include much of western California or any part of Baja California in Mexico, which are instead located on the Pacific plate (see the map posted above for these and other discrepancies). More important, the African plate does not include Madagascar and most East Africa, which are instead on the Somali plate. Most global maps of plate tectonics, however, do not depict the Somali Plate. They presumably do so either for simplification or because the Somali plate is relatively “new,” currently in the process of rifting away from Africa.

Detailed maps of tectonic plates reveal an even more intricate situation. An excellent Wikipedia map, posted below, shows that most of eastern Asia is not necessarily on the Eurasian Plate, but sits instead on the Amur, Yangtze, and Sunda plates. Although the Amur and Yangtze plates can be defined as subdivisions of the Eurasian Plate, the Sunda Plate is more distinct. As its Wikipedia article notes, “The Sunda plate was formerly considered a part of the Eurasian plate, but GPS measurements have confirmed its independent movement at 10 mm/yr eastward relative to Eurasia.” Yet as detailed as it is, this map leaves out several important “micro-plates.” Another Wikipedia map, for example, shows that the Somali plate is itself divided into smaller segments. One of these, the Victoria plate, located between the two arms the East African Rift, is not moving in a single direction, but is rather rotating in a counterclockwise manner.

Detailed Wikipedia Map of Tectonic Plates

A tectonic map that includes all micro-plates can become extraordinarily intricate, as the next post will explore.

Are Continents Rooted in Plate Tectonics? Read More »

Revisiting The Myth of Continents

Article-Grid, Cartography, Continents / Martin W. Lewis

As it has been 28 years since the publication of The Myth of Continents, a book that I jointly wrote with my wife, Karen Wigen, it is time for a reconsideration of the work. The main thesis of the book is that although most continents are rooted in physical geography, the larger continental system of global division is an intellectual construct the veers far from the realities of both the natural and cultural realms. Continents are supposed to be large bodies of land that are separated– or almost separated– from other large landmasses by intervening waterways. But Europe and Asia, the two original continents around which the entire system evolved, have no such separation. Owing to its clunky nature, inconsistencies, and failure to correspond with the most important divisions of either the natural world or humankind, the continental scheme was long ago abandoned by scholars and other serious thinkers. Yet no matter how often it is discredited, the division of the world into a handful of continents remains entrenched, a zombie idea that somehow manages to defy extinction.

My assessments of the impact and success of The Myth of Continents after more than a quarter century are decidedly mixed. One the hand, the book has been by far my most widely cited publication. It still sells relatively well and continues to be used as a text in a few university lecture courses and seminars, mostly in world history. The issues that it explored remain germane and continue to command attention. Every few years, or so it seems, I am contacted by a journalist seeking information on how many continents actually exist and why the landmasses of the world are divided as they are.

But on the other hand, The Myth of Continents has had negligible impact on the public geographical imagination and has had no discernible influence on the way that geography is taught to children and adolescents. Continents are still regarded as the most basic components of world geography, and in the English-speaking world the seven-continent system is still taken-for-granted, as an internet image search for “continents map” quickly reveals. There is little public understanding of the conventional nature of the standard continental scheme, which lacks anything like a secure definitional basis.

Elemental instruction in world geography unfortunately often begins with the seven supposed continents, but that is only one of its many problems. When I see an educational product like the one posted below, my heart sinks. To begin with, the map in this graphic ineptly depicts the world. With a too-narrow Atlantic Ocean, it places Iceland to the northeast rather than to the northwest of Britain. Nor does it get the standard seven-continent model right, as New Zealand, Fiji, and the Solomon Islands, have never, to my knowledge, been classified as parts of the continent of Australia. Most troublesome is the use of a Mercator projection. The Mercator world map, in which the lines of longitude that converge at the poles are rendered as straight, non-converging parallel lines, is a brilliant navigational tool.* It is utterly inappropriate, however, for general-purpose and especially educational maps. Students constantly exposed to such a world depiction are misguided into thinking that Greenland is as large as South America. The result is little short of pedagogical malpractice.

“The Continents of the World” Learning Pack

The Wikipedia article on continents does a commendable job of exploring this complex and fraught topic. It notes that the term “continent” is essentially undefined, and that, as a result, the number of accepted continents varies between four and seven. An animated map admirably depicts these 4-, 5-, 6-, and 7-fold divisional systems. The caption notes that the map only shows “some continents” while further explaining that it groups the “region of Oceania” with the “continent of Australia” through color. The beginning of the article nicely sets a tone of ambiguity:

A continent is any of several large geographical regions. Continents are generally identified by convention rather than any strict criteria. A continent could be a single large landmass, a part of a very large landmass, as in the case of Asia or Europe within Europe, or a landmass and nearby islands within its continental shelf. Due to these varying definitions, the number of continents varies; up to seven or as few as four geographical regions are commonly regarded as continents.

Wikipedia Map of Different Systems of Continental Division

But although this opening paragraph contends that there can be as many as seven continents, the article later allows the inclusion of an eighth, the mostly submerged landmass of Zealandia. It also discusses the existence of “micro” continents; if these are included, the list of continents grows considerable larger. While most micro-continents are arguably too small to merit the designation, Madagascar is a huge island that can easily merit continental status, based on both geological and evolutionary criteria.

Although the Wikipedia article allows the division of the world into more than seven continents, it misses the feasibility of dividing it into fewer than four. But North America can easily be construed as an extension of Eurasia. The waterway separating these landmasses, the Bering Strait, is only 82 kilometers (51 miles) wide and contains several islands in the middle of the passage. More to the point, a vast stretch of the sea separating the two landmasses is very shallow and is underlain by the continental crust of a continental shelf. Over much of the past several hundred thousand years it has been dry land, due to the lower sea-levels that characterized glacial periods (“ice ages”; see the map posted below). This periodic land connection between Asia and North America allowed many temperate-zone and arctic animal species, including humans, to pass between the two “continents,” giving them somewhat similar mammalian faunas. Given the physical connection that exists between North and South America, this perspective yields a three-fold continental division: Antarctica, Australia, and a massive stretch of land that might be dubbed “AmerAfroEurasia.”

Map of the World Divided into Three Continents

If one is thinking in biological rather than geological terms, one might exclude Antarctica from the list of continents, as its macroscopic terrestrial fauna and flora is almost nonexistent. Following this line of thinking, we would then be down to two continents: Australia and AmerAfroEurasia. But the size difference between these two units is so large that that the entire scheme becomes questionable. From this perspective, Australia would perhaps best be seen as an extremely large island, or perhaps as a massive archipelago that encompasses New Guinea and Tasmania.

The next series of GeoCurrents posts will examine in some detail the division of the world into continents, paying attention to its possible usefulness as well as to the problems and paradoxes that it entails. This series will also reexamine the intellectual evolution of the idea of continents, a topic that is covered in some depth in The Myth of Continents. It will begin with an exploration of the geological basis of the scheme, starting with the division of the world into tectonic plates.

The forthcoming GeoCurrents series on continents is part of a larger initiative that I am envisioning that might best be called “advanced elementary geography.” I am also contemplating a related project on “elementary elementary geography,” which would focus on geographical works aimed at children.

*The Mercator projection is the only map projection in which a constant compass bearing can be plotted as a straight line.

Revisiting The Myth of Continents Read More »

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