April 26, 1889.] 



SCIENCE. 



317 



METHODS AND MODELS IN GEOGRAPHIC TEACHING.i 



It is important in teaching the physical geography of the land 

 that the forms of the earth's surface which are to be considered 

 should be selected and arranged in accordance with some natural 

 and if possible genetic system of classification, and that they should 

 be so clearly illustrated as to impress their essential features vividly 

 on the minds of the students. While continental relief and outline 

 should have brief elementary attention, more deliberate study must 

 be devoted to the small rather than to the large areas of the land, 

 the boundary of each area being determined by the extent of a sin- 

 gle kind of structure. A single structural area may be called a 

 geographic " individual ; " and all the individuals of one kind are 

 to be idealized in a type. The types of the land-forms are then 

 to be classified, first, according to their structure ; and, second, 

 according to the degree of advance that they have made in their 

 destructive development, that is, according to their age. Any indi- 

 vidual form may be imagined to pass through a cycle of life, be- 

 ginning when its surface is presented to the destructive forces of 

 the atmosphere, and ending when these forces have reduced the 

 mass to the level of drainage discharge, that is, to the base-level of 

 erosion. The sequence of forms assumed in this cycle of life is 

 highly characteristic, and justifies the use of such terms as 

 " youth," " adolescence," " maturity," and "old age," to indicate 

 the degree of development that the individual has reached. 



Models are employed to impress on the class the essential fea- 

 tures of the various types. The models are of a size large enough 

 to be seen by a class of fifty or a hundred students. They are 

 ■made of paper, colored to indicate certain features, and arranged 

 in nests of two, three, or four, for easy packing. Each nest or 

 group of models represents the successive forms assumed by a 

 single individual as it passes from youth to age. In order to give 

 concrete illustration of their use, the group of forms that may be 

 included under the heading of plains, plateaus, and their deriva- 

 tives," is described at some length. 



A very young plain, like that of the Red River of the North, still 

 retains its embryonic or pre-natal constructional features. It is 

 ■level ; its drainage is poorly developed ; and the few streams that 

 have as yet cut their channels in its surface have only incipient val- 

 leys, narrow and shallow. The future of such a surface would find 

 it traversed by deeper and wider valleys, and broken by more numer- 

 ous side-streams, and the originally smooth inter-stream surface be- 

 comes broken and diversified. While we cannot wait to see this 

 change in the plains of the Red River, we may elsewhere find it 

 already reached in the more advanced or adolescent stage of other 

 plains, born longer ago, such as the coastal plains of the Carolinas. 

 A still later form is found in the sub-mountainous country of West 

 Virginia, where all resemblance to the initial smooth surface is 

 ■long ago lost, but where the horizontal structure of the bedded 

 rocks assures us that in its youth this surface was as smooth as the 

 Red River plains are to-day. West Virginia is in its maturity, for 

 here we have the greatest variety and strength of topographic ex- 

 pression. The drainage is most perfectly developed. The streams 

 are most numerous, and carry at this time the greatest share of 

 land-waste to the sea. Central Kentucky is still further advanced. 

 Here the intensity of relief has diminished ; for, while the hill-tops 

 have lost some of their initial elevation, the valley-bottoms have 

 not correspondingly gained in depth, having already at or before 

 maturity reached close to base-level, below which they cannot 

 •cut. Maturity is passed when topographic expression thus begins 

 to fade. Further advance still more reduces the relief of the sur- 

 face, until in old age the region is a broad low land, whose monot- 

 ony is only here and there relieved by low hills, while idle streams 

 wander on the faintest gradients to the sea. The plains about the 

 upper waters of the Missouri in eastern Montana illustrate this 

 stage, — a broad, gently rolling expanse, overlooked by an occa- 

 sional lava-capped mesa, where erosion has been resisted. When 

 the lava of the cap was poured out from some neighboring vent, 

 it ran down hill to the lowest place that it could find, and there ac- 

 cumulated : the mesas are therefore witnesses to the greater 



' Abstract of a paper read before the Johns Hopkins University Scientific Associ- 

 Jition, Feb. 13, 1889, by Professor William M. Davis of Harvard College. 



^ See an article on this subject in the Proceedings of the American Association, 



height to which the whole surface once rose. And in the denuda- 

 tion of the original mass to its present ultimate form, it must have 

 passed through all the stages represented by the examples already 

 quoted ; it must have had an initial level surface. This was 

 trenched by young and growing valleys, shallow and few in num- 

 ber at first ; deeper, wider, and more numerous later on ; until in 

 maturity there must have been in this now monotonous country a 

 wilderness of rugged hills and a labyrinth of branching valleys. 

 But as the hills wasted away, the land standing relatively quiet all 

 the while, the relief was lessened, and finally the gently rolling 

 plains of the present time were evolved. 



Interruptions in a simple cycle of growth are seen on a closer 

 examination of some of the examples given. The old plains of 

 eastern Montana are no longer lowlands : they are now of consid- 

 erable elevation above base-level ; their rivers are swift, and flow 

 in deep, narrow valleys, even where the rocks are soft and weak, 

 and are interrupted by falls even where the volume of water is 

 large. Manifestly, then, the whole region has lately been up- 

 lifted ; that is, it has entered a new cycle of life, in which it has 

 only reached early youth, and in which, if it is not interrupted, 

 it will pass through another sequence of forms. The region of the 

 high plateaus of Utah, as described by Dutton, is a wonderful ex- 

 ample of the double control of form that appears in individuals not 

 far advanced in a second cycle of growth. The general upland 

 surface had entered maturity while standing at a lower level ; it 

 was then raised several thousand feet, and, thus rejuvenated, is 

 now advanced a little way in its second cycle. The great cafions 

 are only in their youth, though so profound : their depth is a sign 

 of precocity, not of great age. 



Variations in intensity of development characterize different in- 

 dividuals according as they stand at a great or small elevation 

 above base-level. The coastal plains of the Atlantic slope cannot 

 have deep valleys and strong relief, because their valleys are not 

 allowed any considerable depth of cutting ; while the cafions just 

 mentioned give us the climax of intense expression by reason of 

 the great height of the general upland surface over the base-level 

 of the region. 



Inasmuch as the association of topographic features at the sev- 

 eral stages of development is strongly characteristic, it seems ad- 

 visable to recognize this association in the manner ordinarily fol- 

 lowed ; that is, by the use of technical names, of which geography 

 stands in so great need. In the same way, the types of different 

 classes of individuals manifest throughout their life a characteristic 

 succession of forms, such as is well known in those organic forms 

 that undergo metamorphosis. Here again well-defined names 

 applicable to the individuals throughout their whole life may be 

 introduced to great advantage. 



The history of a river may also be illustrated by the series of 

 models, showing the first establishment of stream-courses on the 

 lowest lines offered to the rainfall, the later adjustm.ents and 

 changes of streams by their mutual interaction, the accidents to 

 which streams are liable from climatic change and otherwise. The 

 shifting of streams by the mature adjustments of their drainage 

 areas is regarded as a point of much importance in the develop- 

 ment of the drainage of a region. 



D. C. Heath & Co. will publish at once " The Laws of Health 

 in Relation to School Life," by Arthur Newsholme, M.D., diplomate 

 in public health. University of London. It is a compend of sani- 

 tary science, useful to those who are erecting new school-buildings 

 or modifying those already existing. It is of importance to all who 

 are charged with the responsibility of watching over the mental 

 and physical well-being of pupils of both sexes, in public or private 

 schools or in boarding-schools. It is a book already in use in 

 English training-schools. It has been carefully revised to adapt it 

 to our climate and the needs of American schools. The London 

 AthetKztun says of it, " It is wholly meritorious and altogether free 

 from any blemishes that we can find. There is nothing to be said 

 of it but that it is excellent." Nature says, " Dr. Newsholme has 

 studied his subject thoroughly, and his conclusions are all the more 

 valuable because they have been to a large extent suggested by his 

 experience as a medical officer of health and as a medicinal referee 

 for various schools and training-colleges." 



