MAP OF NORTH AMERICA.
It is supposed that in the course of their study, the pupils have been in the habit of modeling in sand and chalk modeling on the blackboard at every step of the way. It may now be found that they are prepared to represent the entire continent, first in two slopes, again in land masses, and then as an aggregation of river basins, as suggested in the last lesson.
Such a development of the map is illustrated in the present lesson by four stages of chalk modeling. The first stage is represented inFig. 61. It shows the continent of North America in two great slopes, one long one sloping to the east, and a short one sloping to the west, from the line of meeting of their upper edges, or what has been termed the Continental Axis.
Fig. 62represents the continent as sketched after a study of it as simple land masses—a primary land mass, and a secondary land mass, with the line of depression at the meeting of the two opposing slopes. This line is indicated by lines slanting downwards towards the depressed axis.
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The primary land mass is represented as one continuous unbroken land mass extending from the Isthmus of Panama to Behring Strait, and is itself divided into two main slopes. The secondary land mass is likewise divided into two slopes; it is also separated by the St. Lawrence River basin into two parts,viz., the northern or Labrador land mass, and the southern or Appalachian land mass.Fig. 63is drawn to represent the drainage, or principal river basins; as, the Mississippi, Mackenzie, St. Lawrence, and Saskatchawan basins, and the Hudson Bay river system. In drawing small maps on paper it is necessary to trace the rivers with a fine pencil point. For very large maps, four of five feet long, spaces may be left, but great care should be taken to keep them as narrow as possible, so as not to exaggerate the width of the rivers more than is necessary.Fig. 64is drawn in more detail and the great political divisions are marked upon it. On the blackboard map these divisions may be marked with colored chalk, and should follow the contour of the surface as closely as possible.
For the teacher who wishes to rapidly chalk model a map for immediate use in the class, the following hints may be of service:
Plan to draw the continent in its proper proportions within a given space. Imagine that you see it as already drawn. Commence with the region best known or understood, and draw as you mentally travel, to the north, south, east or west. It may be that you will begin with the great depressed regions, in which case draw the ascending slopes and crowning altitudes as you mentally picture; or if the great highlands or water partings are fixed upon as a starting-point, the descending slopes should be drawn to the line of meeting of other slopes, or to the sea level.
Break the line to indicate broken or uneven surface. You will do this naturally, however, if you have in mind the picture of a broken surface.
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Keep the river basins definitely in mind, and the character of streams and rivers: the character also of the land structure; whether it is rocky or alluvial; sharp or hard, or soft and yielding. Knowing that line represents direction, and having a clear and distinct picture in mind of the real country with its surface features, it will be an easy matter to draw or represent it. Understand, as has often been said, that the delineator is drawing from his own mental image of a map, and not copying the work of another. In the latter case no instructions are necessary, as the practice is of no educative value, and should be persistently discouraged.
While at work, always think of the continent as being lighted from one direction, so as to show strong lights and shadows (utilize the blackboard for shadows), this helps to show altitudes; bear in mind, however, that these depend mainly upon direction of line corresponding to direction of surface.
It is to be remembered also, that knowing the geological structure prevents one from drawing level lands first, and from afterward delineating mountains as being piled upon them. Mountains should be drawn where they belong and valleys where they belong, with no contradictory lines underneath to confuse the meaning.
With few exceptions, mountains are the crowning points or peaks of slopes—their meeting place. They may be the corrugated points of mountain ranges or of worn down plateaus.
From whatever part of the continent the work is commenced, let it be carried out in every direction until the limit of land is reached, and then stop. Remember that there is no line between land and water, either at sea-shore or at lake-shore. The rivers may be drawn with charcoal, accentuating the lower part of the river near its mouth.
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Let me say to the beginner—do not let any crude results disturb or discourage you. You can chalk model with an adequate amount of skill if you will. It simply means a close study of nature, a clear knowledge of geographical structure, and persistent effort.
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