In reviewing the directions for chalk modeling, the following points are noted, (a) A mental picture made clearer by expression; (b) A desire to express through the medium of chalk and blackboard; (c) Analysis into terms of drawing, as masses and sub-masses, direction of line, light and shade; (d) Quality of line, attained through “feeling” or harmony with the subject; (e) Artistic expression (no modifications, as erasures or additions); (f) Persistent effort.
Through the observance of the hints given on these points adequate skill in execution may be acquired.
The plateaus of Africa and Australia are classed together in this lesson. Little is known of the western half of the latter, but the eastern half of Australia has its rivers and river basins.
We see also how it has been worn into mountain ranges; the highest part being in the southeast. Africa is also wearing back from the coasts and the plateau itself has many long river basins, the longest of which is that of the Nile. The Nile is not only the longest river in Africa but is the third river of the globe as to length. The valleys of the continent are mostly very narrow, especially the valleys of this river.
The Sahara Desert is represented as being broken into a number of plateaus and depressed regions, which is expressed by short, nearly horizontal lines.
The Abyssinian Plateau is given in detail in Fig. 92. Notice that it lowers gradually towards the south, but abruptly towards the north and that its surface is broken into many plateaus and deeply cut river beds by tributaries to the Nile.
92
MAP OF THE ABYSSINIAN PLATEAU.