Online Encyclopedia

Search over 40,000 articles from the original, classic Encyclopedia Britannica, 11th Edition.

MEXICO (Span. Mejico, or Mexico,)

Online Encyclopedia
Originally appearing in Volume V18, Page 323 of the 1911 Encyclopedia Britannica.
Spread the word: del.icio.us del.icio.us it!

See also:

MEXICO (Span. Mejico, or Mexico,)  officially styled Estados Unidos Mexicanos and Republica Mexicana, a federal See also:republic of See also:North See also:America extending from the See also:United States of America southward to See also:Guatemala and See also:British See also:Honduras, and lying between the Pacific Ocean on the See also:west and the Gulf of See also:Mexico and Caribbean See also:Sea on the See also:east . Its See also:northern boundary See also:line was fixed by the Guadalupe-See also:Hidalgo treaty of 1848 and the See also:Gadsden treaty of 1853; it follows the Rio Grande del Norte from its mouth north-westward to See also:lat . 310 47' N., thence on that parallel W. See also:loo m., thence S. to lat . 31° 20' N., thence due W. to the 111th See also:meridian, thence in a straight line (nearly W.N.W.) to a point on the See also:Colorado See also:river 20 M. below the mouth of the Gila river, thence northward to the mouth of the Gila, and thence, nearly due W., along the old line between Upper and See also:Lower See also:California to a point on the Pacific See also:coast one marine See also:league S. of the southernmost point of See also:San Diego See also:Bay; this line has a See also:total length of 1810 m., of which the Rio Grande comprises 1136 and the See also:land route 674 M . The boundary line with Guatemala, for a See also:long See also:time in dispute, was fixed by the See also:treaties of 1882 and 1895 . It is an arbitrary line and follows only two natural lines of demarcation—the Suchiate river from the Pacific coast to its source, and the Chixoy and Usumacinta See also:rivers from near the 16th parallel N.W. to a point on the latter 25 kilometres, S. of Tenosique (See also:Tabasco) . Between these rivers the boundary line is determined by the peaks of Tacana, Buenavista and Ixbul, and from the Usumacinta eastward it follows two See also:parallels of See also:latitude, one on the point of departure from that river, and the other, the longer, on that of 17° 49' to the British Honduras frontier . The boundary with British Honduras was determined by a treaty of .1893 and is formed in See also:great See also:part by the Hondo river down to the See also:head of Chetumal Bay, and thence through that bay to the Boca Bacalar Chico—the channel separating See also:Yucatan from See also:Ambergris Cay . Geographically, Mexico extends from 14° 30' 42" (the mouth of the Suchiate) to 32° 42' N. lat., and from 86° 46' o8" to 117° 07' 31" W. long . Approximately its greatest length from N.W. to S.E. is 1900 m., its greatest width 750 m., and its least width a little See also:short of 140 M . In outline it is sometimes compared to a huge cornucopia with its small end curving S.E. and N . The interior See also:curve formed by the Gulf of Mexico is comparatively See also:regular and has a coast-line of about 1400 M .

The Caribbean coast-line is about 327 M. long, exclusive of indentations . The See also:

outer curve facing the Pacific is less regular, is deeply broken by the Gulf of California, and has a coast-line of 4J74 m., including that of the Gulf . The See also:peninsula of Lower California (q.v.) lies parallel with the mainland coast and extends southward to about 22° 52'N. lat., a distance of nearly 76o m . The See also:area of Mexico is commonly given by See also:English authorities as 767,005 sq. m., by See also:German statisticians as 1,987,201 sq. kiloms . (767,290 sq. m.), and by H . H . See also:Bancroft, who quotes See also:official figures, as 1,962,899 sq. kiloms . (757,907 sq. m.) . Physiography.—The See also:surface features consist of an immense elevated See also:plateau with a See also:chain of mountains on its eastern and western margins, which extends from the United States frontier southward to the See also:Isthmus of See also:Tehuantepec; a fringe of lowlands (tierras calientes) between the plateau and coast on either See also:side; a detached, roughly mountainous See also:section in the See also:south-east, which belongs to the Central See also:American Plateau, and a See also:low sandy plaincovering the greater part of the Isthmus of Yucatan . The peninsula of Lower California is traversed from north to south by a chain of barren mountains which covers the greater part of its surface . The slopes are precipitous on the east coast, but on the west they break down in hills and terraces to the Pacific . This range may be considered a southward continuation of the Californian Sierra See also:Nevada .

The great plateau of Mexico is very largely of volcanic origin . Its superstructure consists of igneous rocks of all descriptions with which the See also:

original valleys between its marginal ranges have been filled by volcanic See also:action . The remains of transverse and other ranges are to be seen in the isolated ridges and peaks which rise above the level of the table-land, in some cases forming well-defined basins; otherwise the surface is singularly See also:uniform ir, See also:character and level . The two noteworthy depressions in its surface, the Valley of Mexico and Bolson de Mapimi, once contained large bodies of See also:water, of which only small lakes and marshy lagoons now remain . The highest part of this great plateau is to be found in the states of Mexico and See also:Puebla, where the See also:general See also:elevation is about 8000 ft . Southward the slope is broken into small basins and terraces by transverse ranges, and is comparatively abrupt . Northward the slope is See also:gentle, and is broken by several transverse ridges . At See also:Ciudad See also:Juarez (adjoining El Paso, See also:Texas), on the north-ern frontier, the elevation is 3600 ft., which shows a slope of only 41 ft. to the mile . Less is definitely known of the elevated regions of See also:Chiapas, on the border of Guatemala, which are separated from the great Mexican Plateau by the low Isthmus of Tehuantepec (718 ft. at the highest point of the transisthmian railway), but their general elevation is much lower, and they are broken by wooded sierras and eroded by water-courses . The See also:mountain ranges which See also:form part of the great Mexican Plateau consist of two marginal chains known as the Sierra Madre Occidental, on the west, the Sierra Madre See also:Oriental, on the east, and a broken, weakly-defined chain of transverse ranges and ridges between the 18th and 20th parallels known as the See also:Cordillera de See also:Anahuac . All these chains are known locally under diverse names . The Sierra Madre Occidental consists of several parallel ranges in the north, where a broad See also:belt of See also:country is covered with a See also:labyrinth of ridges and valleys .

The most eastern of these are known as the Sierra Tarahumare and Sierra del See also:

Durango, and the most western as the Sierra del Nazareno, Sierra Yaqui and Sierra Fuerte . These converge in See also:southern See also:Sinaloa and Durango to form the Sierra de Nayarit . Near the loth parallel the great chain again divides, the eastern part See also:crossing the southern end of the plateau, and the western, or Sierra Madre del Sur, following the See also:shore line closely to Tehuantepec . The Sierra Madre Occidental has but few See also:note-worthy elevations, its culminating points being the Nevado de See also:Colima (14,363 ft.) - and Volcan de Colima (12,75o ft.) in the See also:state of See also:Jalisco . In the Sierra de Nayarit the Cerro Pirnal rises to an elevation of 11,319 ft., and in the extreme south the Cerro del Leone to 10,302 ft . These sierras lying near the coast have an imposing See also:appearance from the lowlands, but when seen from the plateau their general elevation is so dwarfed as to render them comparatively inconspicuous . The Sierra Madre Oriental consists of a broken chain of ranges extending along the eastern margin of the plateau from the great See also:bend in the Rio Grande south-eastward to about the 19th parallel . In the north these ranges are low and offer no great impediment to railroad See also:building . South of See also:Tampico, however, they are concentrated in a single lofty range . This range extends south-eastward along the western frontier of See also:Vera Cruz (state) and includes the See also:snow-capped See also:cone of See also:Orizaba or Citlaltepetl (18,209 ft.), and the Cofre de Perote, or Nanchampapetl (13,419 ft.) . The eastern slopes are abrupt and difficult, and are a serious impediment to communication with the coast . Rising from the open plateau See also:half way between this range and the See also:city of Mexico is the isolated cone of Malinche, or Malintzin (14,636 ft.) .

Crossing the highest part of the Mexican Plateau is a broken See also:

series of ranges, which form the water-parting between its northern and southern slopes . To a part of these ranges has been given the name ci Cordillera de Anahuac, but there is no true cordillera across this part of Mexico . In a general sense these ranges may be considered part of the eastern See also:branch of the Sierra Madre Occidental, which turns eastward on the loth parallel and crosses the plateau in a south by east direction . Southward the plateau is traversed by many low ranges and breaks down in terraces, forming one of the most fertile and attractive parts of the republic . See also:Close to the See also:capital are the Sierra de Ajusco, whose highest point is 13,078 ft. above sea-level, the Nevado de See also:Toluca (15,168 ft.), in a range which separates the valleys of Mexico and Toluca, the Mantes de See also:las Cruces, and that volcanic, See also:spur-like range, See also:running northward at right angles to the See also:axis of the other ranges, whose culminating points, some 20 m. south-east of the city, are the gigantic, snow-clad volcanoes of See also:Popocatepetl (Smoking Mountain) and Ixtaccihuatl (See also:White Woman) . Both of them are See also:extinct and Popocatepetl no longer smokes . Their elevations, according to the Comisi6n Geografica Exploradora, are 17,888 and 17,343 ft. respectively, that of Ixtaccihuatl being the highest of its three crests . This part of Mexico is highly volcanic in character, the transverse See also:ridge just described having a large number of extinct volcanoes and at least three (Colima, Jorullo and Ceboruco) that are either active or semi-active . Colima was in a state of eruption as See also:late as 1909, Jorullo (4262 ft.) is said to date from 1759, when its cone was formed, and Ceboruco (7100 ft.) in the territory of See also:Tepic, shows occasional signs of activity . Near the coast in the state of Vera Cruz is San See also:Martin, or Tuxtla (9708 ft.), which has been quiescent since its violent eruption of the znd of See also:March 1793 . Orizaba is sometimes included among the semi-active volcanoes, but this is a See also:mistake . It has been quiescent since 1566, and is now completely extinct .

Earthquakes are See also:

common throughout the greater part of the republic, especially on the western coast . They are most violent from San See also:Bias southward to the Guatemala frontier, and some of the See also:Spanish towns on or near this coast have suffered severely . Chilpancingo, in See also:Guerrero, was badly shattered in 1902, and in 1907, and in 1909 was reduced to a See also:mass of ruins . The See also:earthquake shocks of the 30th and 31st of See also:July 1909 were unusually severe throughout southern Mexico, reducing Acapulco and Chilpancingo to ruins and shaking the city of Mexico severely . In Acapulco a tidal See also:wave followed the See also:shock . Slight shocks, or temblores, are of almost daily occurrence . According to See also:Humboldt's theory there is a deep See also:rent in the See also:earth's crust about the 19th parallel through which at different periods the underground fires have broken at various points between the largest of this class, and has the See also:town and See also:port of Carmen at its western extremity . On the northern coast of Yucatan is the small, inhabited See also:island of Holbox or Holboy, and on the eastern coast the islands of Mujeres, Cancum and Cozumel, of which the first and last have a considerable See also:population and See also:good ports . On the Pacific coast there are a number of islands off the rocky shores of Lower California and in the Gulf of California—most of them barren and uninhabitable like the adjacent coast . The largest of these, some of them inhabited, are: Guadalupe—about 75 M. west of the coast on the 29th parallel, which is fertile and stocked with See also:cattle; Cerros, off Viscaino Bay, and See also:Santa See also:Margarita, which partly shelters Magdalena Bay, on the Pacific side; and See also:Angel de la See also:Guarda, Tiburon, San Marcos, Carmen, Monserrate, Santa Catalina, Santa Cruz, San Jose, Espiritu Santo and Cerralvo in the Gulf . Lying off San Blas in the broad entrance to the Gulf are the Tres Marias, and directly west of Colima, to which it belongs, is the scattered volcanic See also:group of See also:Revillagigedo . The See also:peculiar surface formation of Mexico—a high plateau shut in by mountain barriers, and a narrow See also:lowland region between it and the coast—does not permit the development of large river Ao.a SeenMcaol .

P Revillagigedo e/ erarlon la t o prima ll1 nds OSaorro ~ . MEXICO State boundaries State capita a 0 See also:

Railways -.r .. Co.=Cerro C.= Ciudad : . 1.=Aguasenlientes 4.=See also:Tlaxcala 2.=Guannjuato 37=See also:Morelos 3.=See also:Queretaro 6.=Tabasco the Gulf of Mexico and the Revillagigedo Islands . " Only on the supposition that these volcanoes, which are on the surface connected by a See also:skeleton of volcanic rocks, are also united under the surface by a chain of volcanic elements in continual activity, may we See also:account for the earthquakes which in the direction mentioned cause the American See also:continent, from the Gulf of Mexico to the Pacific Ocean, to oscillate at the same time " (Egloffstein, p . 37) . The lowland or tierra caliente region, which lies between the sierras and coast on both sides of Mexico, consists of a sandy See also:zone of varying width along the shore-line, which is practically a See also:tide-water See also:plain broken by inland channels and lagoons, and a higher belt of land rising to an elevation of about 3000 ft. and formed in great part by the debris of the neighbouring mountain slopes . On the Pacific side there are places where the mountain spurs extend down to the coast, but in general this lowland region ranges from 30 to 40 M. in width, except in southern Vera Cruz, Tabasco, See also:Campeche and Yucatan, where it extends farther into the interior . The See also:talus zone of this region, especially at elevations of See also:i000 to 3000 ft., is noted for its great fertility and the luxuriance of its vegetation . There are no large islands on the coast of Mexico, and most of the smaller ones are unimportant . Many of those that fringe the Gulf coast are See also:sand-keys, or parts of a new coast formation . They are commonly barren and uninhabitable .

The See also:

Isla del Carmen, which partly shuts in the See also:Laguna de Terminos (Campeche), is one of See also:emery Waikrr.sa basins . Add to this the See also:light rainfall on the plateau and a lack of forests, and we have conditions which make large rivers impossible . The See also:hydrography of Mexico, therefore, is of the simplest description —a number of small streams flowing from the plateau or mountain slopes eastward to the Gulf of Mexico and westward to the Pacific . Most of these are little more than mountain torrents, but one has a course exceeding 500 m., and few have navigable channels . The See also:principal See also:watershed is formed by the sierras of the state of Mexico, from which streams flow north-east to the Gulf of Mexico, north-west to the Pacific and south-west to the same coast below its great eastward curve . The Rio Grande del Norte, or Rio See also:Bravo, on the northern frontier, is practically an American river, as it rises in American territory and receives very little water from the Mexican side . Its larger Mexican tributaries are the Rio de los Conchos, Salado and Pesqueria . Of the Suchiate and Hondo, which form part of Mexico's southern boundary, the first is a short, impetuous mountain torrent flowing into the Pacific, and the other a sluggish lowland stream rising in north-eastern Guatemala and flowing north-east through a heavily forested region to Chetumal Bay . The peninsula of Yucatan has no rivers, and that of Lower California only a few insignificant streams in the north . This is due to the porosity of the See also:soil in the former, and the very limited rainfall in the latter . The largest rivers of Mexico are: the Rio Grande de See also:Santiago, called the See also:Lerma above See also:Lake Chapala, rising in the state of Mexico and flowing westward across See also:Guanajuato, Jalisco and Tepic to the Pacific coast, with a total length of 540 m., celebrated for its deep canyons and waterfalls; the Rio de las Balsas, or Mescala, which rises in Tlaxcala and flows south and west to the Pacific with a course of 426 M.; the Yaqui, which rises in western See also:Chihuahua and, after breaking through the northern ranges of the Sierra Madre Occidental, flows south-See also:westerly across Sonora to the Gulf of California, with a length of 390 m.; the Grijalva, also called the Chiapas on its upper course, which has its See also:sources in the state of Chiapas and flows north-west and north across Tabasco to the Gulf of Mexico, with a total length of 350 m.; the Fuerte, which rises in southern Chihuahua and, after breaking through the sierras, flows south-west across Sinaloa to the Gulf of California, with a course of 340 m.; the Usumacinta, which is formed by the confluence of the Chixoy and Pasion on the east frontier of Chiapas, and flows north-west across Tabasco to the Grijalva, with a course of 330 M.; and the Panuco, which has its source in the north-west of the state of Mexico and flows north-eastward to the Gulf of Mexico . The rivers of the Pacific coast have no navigable channels See also:worth mentioning, but many on the Gulf coast are navigable for considerable distances .

The more important of these are in Tabasco—the Grijalva, navigable for about 93 m., and the Usumacinta, for about 270 M . The country about the Laguna de Terminos is low and See also:

flat, and is traversed in all directions by deep, sluggish streams . Many of the rivers crossing the lowlands bordering the Gulf have short navigable channels, the most important of which is the Panuco and its tributaries . The Rio Grande is navigable for small vessels up to See also:Matamoros (31 m.), and for smaller See also:craft 65 m. farther . Nearly all the Gulf coast rivers, however, are obstructed by bars owing to the quantity of silt brought down from the sierras and the prevailing winds and currents on the coast . The lakes of Mexico are small and few in number . They may be divided into two classes ;.those of the plateau region which occupy lacustrine depressions and receive the drainage of the surrounding country; and the tide-water lagoons of the coast formed by the building up of new sand beaches across the indentations in the coast-line . Of the former, the best known are the lakes of the Valley of Mexico—Texcoco, Chalco, Xochimilco, Zumpango, Xaltocan and San Cristobal—which are probably the remains of a lake once occupying the whole valley . They receive considerable surface drainage, but are slowly diminishing in area . Some of them, like Xochimilco, will eventually disappear . The largest, Texcoco, has an area of about iii sq. m . (30 sq. kiloms.), but it covered a much larger area at the time of the Spanish See also:conquest .

Its surroundings are See also:

bleak and sterile and its See also:waters brackish and polluted with the drainage of the neighbouring city for nearly four centuries . The other lakes are wholly different in character and surroundings, especially Chalco and Xochimilco . Texcoco is now connected with the new drainage See also:works of the capital and is no longer a menace to its population through inundations and pestilential fevers . Another group of lakes is to be found in the Laguna See also:district of south-western See also:Coahuila, where the Tlahualila, Mairan, Parras and others occupy a large lacustrine depression and receive the waters of the Nazas and Aguanaval rivers from the south-west (Durango) . The See also:size of this isolated drainage See also:basin is very large, the Nazas River alone having a length of about 370 M . The great Mapimi See also:desert of western Coahuila is another lacustrine depression, but only marshy lagoons remain . In eastern Coahuila, near Monclova, are the Agua Verde and Santa Maria lakes, and in eastern Chihuahua there is a similar group . The largest and most attractive of the plateau lakes is Chapala, in the state of Jalisco, about 8o m. long by 10–35 M. wide, which receives the waters of the Lerma and discharges into the Pacific through the Santiago . On the lower terraces of See also:Michoacan are Patzcuaro and Cuitzeo lakes, and elsewhere among the sierras are numerous other small bodies of water . Among the tide-water lagoons, of which there are many along the Gulf coast, the best known are the Laguna de Terminos in Campeche, Tamiahua in Vera Cruz, Madre (130 M. long), Pesquerias (21 M. long) and Chairel (near Tampico) in See also:Tamaulipas . All these lagoons are navigable, and those of northern Vera Cruz and Tamaulipas, when connected and improved, will afford a safe inland route for some hundreds of See also:miles along the coast . The north coast of Yucatan is remarkable for the extensive See also:banks built up by the Gulf current from 5 to 7 m. from the shore-line .

Inside the See also:

present sandy coast is a peculiar tide-water channel called the Rio Lagartos, which follows almost the whole northern shore, with occasional openings or bocas, connecting with the open sea . It is apparently of the same character as the lagoons of Tamaulipas . There are a number of these lagoons on the Pacific coast—such as See also:Superior and Inferior near See also:Salina Cruz, Papacayo, near Acapulco, Cayutlan, near See also:Manzanillo, and Tecapan in Tepicbut they are usually shallow, sometimes swampy, and have no value for See also:commerce . There is a marked difference between the Gulf and Pacific coast-lines of Mexico in regard to their See also:minor indentations and harbours . The south-west part of the Gulf of Mexico is called the Gulf of Campeche (Campeachy), but no distinction is necessary . This coast has no bays of importance, its rivers are obstructed by sand-bars, and it has only one natural See also:harbour--that of Carmen and the Laguna de Terminos, which has sufficient See also:depth for the larger classes of vessels and is sheltered by the islands of Carmen and Puerto Real . Of the principal ports on this coast, Matamoros, Tampico, Tuxpan, Coatzacoalcos and Frontera are on rivers, which are obstructed by bars . Tampico and Coatzacoalcos, how-ever, have been improved by breakwaters or jetties, and the deepening of the Channels across the bars, into safe and commodious harbours . Vera Cruz is an open anchorage inside a series of reefs which afford no See also:protection to vessels from the " northers." A See also:breakwater has remedied this defect and . Vera Cruz is no longer considered a dangerous port . Campeche has a small artificial harbour, which is so silted up that vessels See also:drawing 9 ft. must See also:anchor 1 m. outside and larger vessels still farther away . Progreso, Yucatan, has only an open roadstead, and large vessels cannot approach its landing-See also:place nearer than 6 m .

On the east coast of Yucatan there are two deep, well-sheltered bays, See also:

Ascension and Espiritu Santo, which afford good anchorages, and at the north end of the island of Cozumel the bay of Santa Maria offers an excellent harbour . The Pacific coast has several deep and well-sheltered bays; but they are separated from the interior by the rough and difficult ranges of the Sierra Madre Occidental . There are two large indentations of the coast—the Gulfs of Tehuantepec and California . The former is opposite the Gulf of Campeche, and possesses no distinguishing characteristic . The Gulf of California, on the other See also:hand, penetrates the continent for a distance of 739 m., from south-east to north-west, with a maximum breadth of 190 M . Its area is usually restricted to the waters north of the latitude of Cape San See also:Lucas, but it should be extended to the outer waters enclosed by a line from Cape San Lucas to Cape See also:Corrientes . Its upper waters are not much navigated because of the aridity of its coasts, but there are two or three important ports towards the south . The Gulf has a considerable number of islands, most of them near the See also:peninsular coast, and several deep, well-protected bays—those of La Paz and Santa Ines in Lower California, See also:Guaymas in Sonora, Agiobampo, Topolobampo and Altata Salinas in Sinaloa . On the Pacific coast of Lower California are the See also:Ensenada de Todos See also:Santos and the bays of San Quentin, Viscaino and Magdalena . The principal bays on the mainland coast are Olas See also:Atlas, which is the harbour of See also:Mazatlan, San Blas, Banderas, Manzanillo, Acapulco, Salina Cruz and Tonala . Several of these are being improved . [See also:Geology.—By far the greater part of Mexico is covered by deposits of Cretaceous and later date, the pre-Cretaceous rocks occurring only in comparatively small and isolated patches .

At the southern extremity of the great table-land, however, in the state of Puebla, there is a considerable mass of crystalline rocks which is believed to be of Archaean See also:

age . Similar rocks occur also in Chiapas, See also:Oaxaca, Guerrero and elsewhere; but owing to the See also:absence of any See also:early fossiliferous deposits, the age of these rocks is very uncertain . See also:Silurian and Devonian fossils have been reported at one or two localities, but for the present the observations are open to doubt . The earliest fossiliferous beds which have been proved to exist in Mexico belong to the Carboniferous See also:system . They are found on the See also:borders of Guatemala and consist of limestones and See also:dolomites with Productus . The Mesozoic beds are of greater importance . The Triassic and See also:Jurassic systems are met with only in scattered patches . The former consists of sandstones and See also:clays, and the fossils found in them are chiefly See also:plants, including Gangamopteris and Macrotaeniopteris, two characteristic genera of the See also:Indian See also:Gondwana system . The Jurassic beds are marls, sandstones and limestones, which contain marine fossils . The Cretaceous rocks take a far larger See also:share in the formation of the country . They form the greater part of the Sierra Madre Oriental and also See also:cover most of the central plateau . They contain many fossils, including Hippurites and See also:Ammonites .

The sedimentary deposits of the See also:

Tertiary era do not occupy a very wide area . They occur, however, along the coasts, where they are marine, and also on the central plateau, where they are of lacustrine origin . But by far the most important of the Tertiary rocks are the volcanic lavas, agglomerates and ashes, which cover so much of the country . It is in the western half of Mexico that they are most fully See also:developed, but towards the southern extremity of the plateau they spread nearly to the eastern coast . The eruptions are said to have begun with the ejection of syenites, diorites and diabases, which probably took place at the close of the Cretaceous or the beginning of the See also:Eocene See also:period . In the See also:Miocene period andesites of various kinds were erupted, while at the close of the See also:Pliocene began the great eruptions of See also:basalt which reached their maximum in See also:Quaternary times and continue to the present See also:day.' (P . LA.)] See also:Climate.—Mexico stretches across 17 parallels of latitude, with the Tropic of See also:Cancer crossing her territory about midway . This implies tropical and sub-tropical conditions . The See also:relief of the land and varying degrees of rainfall and vegetation, however, serve to modify these conditions in many important particulars . The elevation and extent of the great central plateau, which penetrates ' See J . G . See also:Aguilera, Sinopsis de geologia mexicana; " Bosquejo geologico de Mexico," segunda parte, Bol. inst. geol., Mexico, Nos .

4–6 (1897), pp . 189–270, with See also:

map—a See also:summary of this See also:paper will be found in See also:Science Progress, new series (1897), vol. i. pp . 6o9–615 . See also the Livret-See also:guide of the Tenth Cong . Geol . Internat . (1906) . deeply into the tropical half of the country, carry with them-temperate and sub-tropical conditions over much the greater part of the republic . Above the plateau rise the marginal sierras, while a few isolated peaks in the region of perpetual snow give to Mexico a considerable area of See also:cold temperate and a trace of See also:arctic conditions . Descending to the lowlands on either side of the plateau, the temperature rises steadily until the upper limit of the tropical region, called tierras calientes, is reached, where the climate is hot, humid and unhealthy, as elsewhere in the forested coastal plains of tropical America . The tierras calientes (hot lands) of Mexico include the two coastal zones, the Isthmus of Tehuantepec, the states of Tabasco, Campeche, and part of Chiapas, the peninsula of Yucatan and a part of eastern Oaxaca . The mean temperature ranges from 77° to 82° F., seldom falling below 6o°, but often rising to 105°, and in the sultry districts of Vera Cruz, Guaymas and Acapulco to and even above 11o° .

Phoenix-squares

The rainfall is heavy in the south, except Yucatan, but diminishes gradually toward the north, until on the Pacific and Gulf of California coasts it almost disappears . These lowland districts are densely forested in the south, except Yucatan, and large areas are covered with streams, swamps and lagoons, the See also:

abode of noxious See also:insects, pestilential fevers and See also:dysentery . On both coasts yellow See also:fever epidemics appear at frequent intervals . The great fertility of these regions and the marvellous See also:wealth of their forests are irresistible attractions to See also:industrial and commercial enterprise, but their unhealthiness restricts development and is a See also:bar to any satisfactory increase in population . The heavy rainfall on the Gulf coast, however, which reaches a maximum of 90 to 100 in. in the Huatusco district of Vera Cruz, causes the flooding of large areas of lowlands, and will make improvement very difficult . The peninsula of Yucatan, whose general level does not rise above 130 to 200 ft. above the sea, consists almost wholly of an open, dry, calcareous plain . The temperature ranges from 66° to 89°, but the See also:heat is tempered by the cool sea-breezes which sweep unobstructed across its plains . The rainfall is abundant in the See also:rainy See also:season, but in the long dry season it is extremely rare . In the wet season the See also:rain is quickly absorbed by the dry, porous soil; consequently there are no rivers and no lakes except near the forested region of the south-east . These exceptional conditions give to Yucatan a moderately hot, dry, and comparatively healthful climate . Another hot, dry climate is that of the tierras calientes of Sonora . The coast is low and extremely arid, and would be uninhabitable were it not for the proximity of the Sierra Madre, where a light rainfall is experienced, and for the numerous rivers that See also:cross the arid belt between the mountains and the sea .

The maximum temperatures in this region are 98° at Hermosillo and 119° at Guaymas . To a large extent the climate of Mexico is determined by See also:

vertical zones . According to H . H . Bancroft (Resources of Mexico, pp . 3-4), the tierras calientes, which include a coastal zone 30 to 40 M. wide and the low-lying states already mentioned, rise from sea-level to an elevation of 3280 ft . The tierra templada, or sub-tropical zone, rises to an elevation of 5577 ft., and comprises " the greater portions of Coahuila, Nuevo See also:Leon, an Luis See also:Potosi, nearly half of Tamaulipas, a small part of Vera Cruz, nearly the whole of Chiapas, nearly all of Oaxaca, a large portion of Guerrero, Jalisco, Sinaloa and Sonora," together with small parts of the inland states of Puebla, Mexico, Morelos and Michoacan . The mean See also:annual temperature is about 75° . Above this is the tierra fria, which ranges from 5577 to 8200 ft., and includes all the higher portions of the Mexican plateau, and which corresponds to the temperate regions of Central United States where frosts are very rarely experienced . Even here the high See also:sun temperatures give a sub-tropical character to the country . In the sierras, above the tierras frias, which are not " cold lands " at all, are the colder climates of the temperate zone, suitable for cereals, grazing and See also:forest See also:industries, and, farther up, the isolated peaks which rise into the regions of snow and See also:ice . Speaking generally, the four seasons are clearly marked north of lat .

28° N. only . South of that parallel they See also:

merge in the estaci6n de las aguas, or rainy season, from May to See also:October, and the estaci6n seta, or dry season, which prevails for the See also:rest of the See also:year . The rains generally begin on the east coast and gradually move northwards . The windward slopes of the Sierra Madre Oriental receive the greater part of the rainfall, and the winds, deprived of their moisture, pass over the northern plateau without further precipitation . On the Pacific coast the belt of calms, known as the northern See also:horse latitudes, crosses the northern parts of Lower California and Sonora, which accounts for their extreme aridity . The southern terraces of the plateau have no high mountain barriers between them and the moist winds of the Caribbean, and they too receive an abundant rainfall in the wet season, especially during the prevalence of heavy " northers " on the Gulf coast . The precipitation varies widely, that of the western side of the northern plateau (Chihuahua and Durango) being about 39 in., that of the Valley of Mexico about 25 in., and that of the whole republic 59 in . Long droughts are common in many parts of the country, and on the barren surfaces of the plateau the rains drain away rapidly, leaving but slight beneficial results . See also:Flora and See also:Fauna.—The types of See also:animal and See also:vegetable See also:life found in Mexico belong, in a general sense, to those of the northern See also:temper-See also:ate region, and those of the tropical' regions of Central and South America . The great central plateau and its bordering lowlands form an intermediate territory in which these dissimilar types are found side by side, the tropical See also:species extending northward along the coast to the United States, while the northern species have found their way to the southern limits of the plateau . The See also:jaguar and See also:puma have found their way into the United States, while the See also:wolf, See also:coyote, See also:bear and See also:beaver have gone far southward on the plateau, and the See also:buffalo was once found in large See also:numbers on its more favoured northern plains . This intermingling of types does not apply to south-eastern Mexico, where animal life is represented by many of the genera and species found in the forested lowlands of the great See also:Amazon basin .

Aside from its origin, the fauna of Mexico includes at least five species of See also:

monkey, the jaguar, puma, See also:ocelot (Felis pardalis), wolf, coyote, See also:lynx, See also:badger, See also:otter (Lutra felina), beaver, muskrat, bear, See also:raccoon (Procyon), See also:coati (Nasua), See also:tapir, two species of See also:peccary (Dicotyles torquatus and D. labiatus), See also:skunk (Mephitis, Spilogale and Conepatus), See also:marten, several species of See also:opossum (i