The central division or °Central Andesb the name proposed by Mr. Bowman for a group of closely related natural regions that lie be tween 12° and 26° south latitude — may now, in turn, receive brief attention. Here the dominat ing features are two great plateaus with a cen tral basin between them. These plateaus, trend ing north and south, are depicted on the physical maps as two roughly-parallel mountain chains, commonly referred to as the eastern and western 'central] Andes. In Bolivia, these east-central Andes are variously designated as the Cordil lera Oriental, Cordillera of the East, or the Cordillera Real, the latter being an improper extension of the specific term applied to the high, white, truly "royal and regal" mountain range near La Paz that is terminated on the south by Illimani and on the north by Sorata. The west-central Andes are usually called the Maritime Cordillera, a generic term applied to the aggregations of individual peaks and short volcanic ranges which surmount the western plateau. In addition, specific terms are applied to the culminating ranges. Thus, on the boundary between Chile and Bolivia, lat. 20° S., there is the Cerro de Sillilica, just as in south ern Peru the mountain knot at Vilcanote is called the Cerro de Vilcanote. In the eastern plateau the exceptional heights or the crests of the declivities that border basins and valleys are given such specific names as the Tunari de Cochabamba, Cerro de Cliza and Cordillera de Potosi. Between the two great Andine table lands and their superimposed peaks and ranges is the central basin or plateau of lower altitude than the bordering highlands, separated from the latter by the two great roughly-parallel scarps of marked rectilinear quality often for long distances. This is the alti-plano of Bolivia: an interior drainage basin, with no visible out let to the sea, and therefore technically a part of the true desert area of the world. On the north the bordering scarps converge in lat. 14° S., enclosing Lake Titicaca, whose waters discharge by way of the Desaguadero River into Lake Poop& only to be discharged in turn into the Salar de Coipasa and the adjacent salars to the south. Here and there the otherwise flat basin floor is broken by piles of volcanic detritus, lava flows from occasional centres of igneous activity, or by ancient and highly crumpled sedimentaries, as where the upturned edges of slates and quartzites rib the hills back of the port of Desaguadero. East of the central Andes, as indeed along the whole eastern front of the Andine Cordillera, from the Argentine Pampas to the Llanos of Vene zuela, the dissection of the adjacent highlands has been accompanied by the formation of ex tensive piedmont deposits. The western plateau descends by a relatively smooth slope to the coastal deserts of Tarapaci and Ata cama. Between these deserts and the Pacific shore are low mountain ranges of complex geologic and physiographic character, the coast ranges of Chile and Peru.
A generalization by Mr. Bowman is to the effect that, in the field of human geography, the central Andes form an exceedingly im portant group. It is impossible to find else where in South America an area of equal size with so great a variety of life. The density of population ranges from 100 to the square mile in the vicinity of Cochabamba, Bolivia, to one tenth to the square mile in the Tcrritorio de los Andes, Argentina. Occupations vary between such extremes as, on the one hand, the inten sive agriculture of irrigated valleys, and on the other the pastoral nomadism of Alpine meadows: customs are, in one place, those of modern civilized people, but, in another, those i that bespeak an unmixed barbarism. It is the extremely wide range in the physical condi tions of the central Andes that the in terest of the geographer. The principles of geographic science rest upon the theory that man is to an important degree the product of the earth. In the varied physical environment
of this great tract we should therefore expect climate and relief to exercise a high degree of influence upon the population. A study of its people should demonstrate both the scientific nature of geography and the wide application of its laws.
The fourth division, according to the order we are following from south to north, is the equatorial; and here we notice the points in which this region is sharply differentiated from the other divisions. Edward Whymper, the dis tinguished explorer, in his 'Travels' wrote: "In a very short time it was found that there were things to be unlearned as well as dis covered in Ecuador. We ascertained that Chimborazo streamed with glaciers, although high authorities state that it has none; and in course of time it became apparent that the two 'parallel Cordilleras,' which according to geographers are the great feature of the coun try, do not exist.° By an equatorial belt, so to speak, the parallel cordilleras observed hitherto (in this article) are constricted. But these soon diverge above the line, and more than re assert their individualism before yielding to that powerful eastern impulse which we have already mentioned in the first paragraph. The axis of the Andes in Ecuador runs nearly north and south; and toward the western edge of the main chain there is indeed, this author admits, a certain sequence of peaks more or less in a line. East of these summits there is a succession of basins of different dimensions and at various elevations. The nearest moun tains on the eastern side occur at irregular distances. There is no such thing as one great valley in the interior of Ecuador. The moun tains Pasochoa and Ruminahui are the only two which lie parallel to the others on the western side. All of the great Andes of the equator rise out of, or upon and above, the main chain, which was created by upheaval at some remote date (compare what has been said above in respect to time). With the exception of Sara urcu, they are all mountains of volcanic origin, although they may not all have been active volcanoes. It seems probable that there were never many of these volcanoes in activity at any one moment. Some that are now extinct have evidently been alive; while others, like Pichin cha and Tunguragua, are either dormant or are not perpetually in eruption. Cotopaxi and Sangai alone are in a state of constant activity, and these two mountains seem to be increasing their elevation. Cotopaxi shows no signs of approaching decrepitude, and for many cen turies yet to come it may remain the highest active volcano in the world. In general the altitudes here are less by several thousand feet than those of the highest peaks in Chile and Bolivia. Of the extinct volcanoes, Cayambe, Antisana and Chimborazo are the most import ant. There are no records of eruptions of Chimborazo. It must have been an extinct vol cano for many ages. The complete burial of its crater, the thickness of the ice-cap at its sum mit and the large size of its glaciers, the ruin and erosion of its lava-streams and the height vegetation has attained upon its flanks, are all indications that its activity ceased at a remote period. Particularly interesting are the obser vations of temperatures on summits in Ecuador. On 4 January at 5:15 P. i.e. the temperature on the summit of Chimborazo (height 20,498 feet) was found to be 21° F., while at Guayaqdil (6 P. M. on the same day) it was F. On 18 February at 6:20 A. M. the temperature on the summit of Cotopaxi (height 19,613 feet) was 21° F. At Guayaquil on the same day at 11 A. M. the temperature was 82° F. On 10 March at 10-11:40 A. M. the temperature on the sum mit of Antisana (19,335 feet) was F., while at Guayaquil on the same day at 11 A. at. it was 80° F. In each case the observations were, of course, of temperatures in the shade.