TNPSC General Studies Geography free study course. TNPSC Study Materials UNIT 3 for Group 1, 2 & 2A, 4 & VAO. Behavioral geography is an approach to human geography that attempts to understand human activity in space, place, and environment by studying it at the disaggregate level of analysis—at the level of the individual person.

As people travel, they encounter different environments and peoples. Such variations are intellectually stimulating: Why do people and places differ? Stores of knowledge were built up about such new and exotic places, as demonstrated by the Greek philosopher and world traveler Herodotus in the 5th century bce. That knowledge became known as geography, a term first used as the title of Eratosthenes of Cyrene’s book Geographica in the 3rd century bce. Such was the volume of knowledge compiled thereafter that Strabo’s Geography, published three centuries later, comprised 17 volumes. Its first two provided a wide-ranging review of previous writings, and the other 15 contained descriptions of particular parts of what was then the known world. Soon thereafter Ptolemycollated a large amount of information about the latitude and longitude of places in his seminal work.

The Greeks and Romans not only accumulated a great body of knowledge about Earth but also developed the sciences of astronomy and mapmaking, which helped them accurately locate places. However, during western Europe’sMigration period (Dark Ages), much of that wisdom was lost, but the study of geography—notably cartography—was nurtured in the Arab world. This material became known to western Europeans during medieval times, partly through their contacts with the Muslim world during the Crusades. As the Europeans linked this new material with what. they could rediscover in ancient Greek and Roman work, they frequently stressed misinformation derived from the latter, notably in Ptolemy’s inaccurate maps. From then on, as Europeans explored more of the world, increasing numbers of scholars collated new information and transmitted it to wider audiences.

A key feature of geographical information is that it is localized, relating to individual parts of Earth’s surface. Geography involves recording such information, in particular on maps—hence its close links with cartography. For centuries the locations of places were only inexactly known. Where to plot information on maps was frequently debated, as was drawing and demarcating boundaries around claimed territories. These debates were only resolved with more accurate and standardized cartographic practices. Meanwhile, collections of maps were assembled and published in atlases, a term first used by the 16th-century Flemish surveyor and cartographer Gerardus Mercator (Gerhard de Cremer) for his collection of maps of northern Europe, published in 1595; the first collection of maps of the world, Epitome of the Theatre of the World (1570), was produced by Mercator’s contemporary, the Belgian cartographer Abraham Ortelius. The science of surveying was employed to make detailed large-scale maps of the land surface; notable was the work of the Cassini family, in France, spanning more than a century, which was the basis for the world’s first national atlas, published in 1791.

Define biosphere geography

Thus, the evolving practice of geography involved mapping the world, drawing outlines of what heretofore were terrae incognitae, and filling them in with details about their physical environments and the people inhabiting them. Such geographical advances depended on improvements not only in cartography but also in astronomy, which was vital for navigation. Methods for determining latitude and longitude and measuring elevations and distances were refined and were of great value to navigators and explorers and their sponsors. Many expeditions, such as those of James Cook in the second half of the 18th century, conducted scientific experiments that enabled advances in navigation and cartography and collected samples of flora and fauna that were used to classify knowledge about the natural world—as in the pioneering work of the 18th-century French naturalist Georges-Louis Leclerc, comte de Buffon. These links between geography, exploration, cartography, and astronomy have been maintained, appearing as the first sections of many contemporary atlases (with maps of the heavens along with terrestrial phenomena such as climate).

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As information accumulated, a new branch of geography was established by the late Middle Ages, called chorography (or chorology). Books describing the then known world were used in geographical instruction at universities and elsewhere. Geography was not a separate discipline but was taught within established subjects such as mathematics and natural philosophy, in large part because it was of great importance to nation building and commerce. Among the early geography books were Nathaniel Carpenter’s Geography Delineated Forth in Two Bookes (1625) and the German scholar Bernhardus Varenius’s Geographia Generalis (1650), which was revised and republished several times in the following century. Canadian geographer O.F.G. (George) Sitwell’s catalog lists 993 different books in “special” (i.e., systematic) geography published between 1481 and 1887 in the English language; Lesley Cormack identified more than 550 geography books in the libraries of the Universities of Cambridge and Oxford in the period from 1580 to 1620.

Geography was practiced and taught largely because its information was valuable—notably for traders, those who invested in them, and the statesmen who supported both groups. By the early 19th century there was great demand for information and knowledge about the world. To aid commercial enterprises aimed at exploiting its resources and peoples, governments became involved in colonial ventures, annexing land beyond their frontiers, providing administrators and military protection, and encouraging settlement. All such endeavours required geographical information, including accurate maps. Increasingly, governments became directly involved in these activities, as with the U.S. government’s sponsorship of major expeditions to the country’s expanding western frontier and the establishment of national mapping agencies around the world.

Geographical societies were established in many European and North American cities in the early 19th century to share and disseminate information. Among the first were those founded in Paris (1821), Berlin (1828), London (1830), St. Petersburg (1845), and New York City (1851). Many of the European societies had royal patronage and strong support from the mercantile, diplomatic, and military classes. They collated and published information, sponsored expeditions, and held regular meetings, at which returning explorers might present their findings or participate in debates over technical issues such as mapping. These societies were central to the 19th-century mercantile and imperial ethos.


In this article we will discuss about the extinction of animals that takes place in a number of ways due to variety of causes.

Speciation (evolution of new species) and spe­cies extinction (complete elimination of species) are the natural processes which follow the evolution of animals. It is believed that about 200 species of mam­mals and birds have become extinct for the last 2000 years. Though there are several natural causes of species extinction but the modern man has accelerated the pace of animal extinction.

The number of a few species of animals has come down to such a small size that if they are not provided immediate protection, they will soon become extinct. For example, the total popu­lation of 150 species of birds is believed to be only 2000 at present time, short-tailed albatrosses are only 100 in number and about 100 mammals are facing immediate extinction.

Biosphere Geography A Level


Extinction of animals may take place in a number of ways due to variety of causes as given below:

(i) It is an established ecological principle that the environmental conditions of any region may change. The change may be gradual and long-term or it may be sudden and short-term. If the environmental condi­tions of any region change gradually, the animals of that region also try to adjust and adapt to new environ­mental conditions and sometimes they become suc­cessful to survive.

But if the environmental conditions change so rapidly that the animals are unable to adapt to new changed environmental conditions, several species become extinct. In other words, if the rate of environmental change exceeds the rate of adaptation by animals to change environmental conditions, many species become extinct.

The mass extinction of dino­saurs is believed to have been effected because of sudden drop in temperature during the early period of Tertiary Epoch. The dinosaurs having a large body and un-proportionately long tail could not move to other places to escape from the excessive cold and therefore they perished and became extinct.

(ii) The sudden outbreak of disease and pest infections caused by changed environmental condi­tions of the regions concerned causes species extinctions.


(iii) Some sudden events like forest fires, vol­canic eruption etc. cause species extinction. Violent explosion of Kratatao in 1883 led to mass extinction of species of that island.

Define Biosphere Geography

(iv) Direct hunting and persecution of species lead to selective mass extinction.

P.S. Martin (1967) has suggested three alternative hypotheses of ‘selective mass extinction’:


(a) Ecological substitution by other species of large carnivorous animals which compete for the same food resources.

Biosphere Geography

(b) Climatic change accelerates the competition between large mammals for shelter and food.

(c) Over-killing of certain species by man.

Ecosystems Geography

(v) Some weaker species become extinct as these perish during the course of competition with most powerful and strongest species.

Higher Geography Biosphere Model Answers

(vi) Man-induced environmental changes also cause species extinctions. Man changes the environ­mental conditions both intentionally and unintention­ally through a variety of his activities e.g. habitat removal, land use changes, weather modifications, chemical and atomic wars etc. Human activities also alter the equilibrium state of ecosystem which causes extinction of some species at local scale or regional scale.

Biosphere Geographical Definition

Man’s continued interference with natural envi­ronment at local and regional levels has led to destabilization of environmental and ecological equi­librium and several species of animals are facing threatened extinctions.

According to R. Silverberg (1973) only two kinds of mammals became extinct at world level during 1801-1850; the period 1851-1900 registered upward trend in the species extinction as 31 kinds of mammals became extinct; there were extinctions of 41 kinds of animals in the next period from 1901 to 1944.

Higher Geography Biosphere

It may be pointed out that extinction is an inherent natural ecological process and there is natural balance or dynamic equilibrium between speciation, dispersal and extinction but man-induced extinction may upset this balance which may cause hazardous and disastrous ecological problems to human society.