Lessons in chalk modeling: The new method of map drawing

by Ida Cassa Heffron

Having a general idea of the geographical features of Mexico, the pupil in its closer study, may give its location as lying south of the United States and extending from Texas on the north to central America on the south. He may describe its general shape as triangular or cornucopia shaped. He may notice that the Rio Grande forms its natural boundary on the north, for nearly three fourths of the distance from gulf to ocean. What is the length of this river? Compare with length of the Mississippi. How far is it navigable? (About 500 miles.) What is its character? (Swift, crooked, and obstructed by rapids and sand-bars.) Notice the break in the great western range of mountains, forming a depression between the Sierra Madre and Sierra Nevada Ranges.

Just north of this break and west of the Colorado River, in the state of California, lies the great Mohave Desert, in which is the famous “Death Valley,” 100 feet below the level of the sea.

From the Gulf of Mexico on the east and the Pacific Ocean on the west the land rises in a succession of terraces or plateaus, with elevations varying from 2,000 feet to 8,000 feet above sea-level.

The great central or upper plateau has an elevation of about 3,000 feet at the north, but ascends gradually to the height of 8,000 feet in the southern part. Compare this with the Mohave Desert. With the great plateau of the United States. With Florida (mean elevation 30 feet). In this part, the eastern mountain wall of the great central plateau, and the western, which is much higher of the two, culminate in a knot of lofty mountains. This is a volcanic region, and here a number of isolated volcanoes tower above the uplands in a line from east to west. Of these snow-capped volcanoes the highest are Popocatapetl and Orizaba, which are about 17,500 feet above the sea-level.

Compare these with the highest peaks of the Rockies. From this point the land abruptly lowers to the low Isthmus of Tehuantepec and the Peninsula of Yucatan. Mexico has an area of 744,000 square miles. Compare with area of the United States (3,605,000).

Why are there more rivers flowing into the Gulf of Mexico than into the Pacific Ocean? Where is the greatest rainfall? What is the direction of the prevailing wind? Can this be known from the map? The average annual rainfall at the Gulf Coast is 150 inches. How does this compare with that of Florida? (60 inches.) With that of Chicago? (36 inches.) What is the rainfall on the western coast? (There is scarcely no rain at all.) Why? Where is the source of the rivers on the west coast? The average rainfall of the plateau is 27 inches. May we expect to find many rivers flowing from it? What is likely to be the character of rivers flowing into the Gulf? (They are swift torrents bearing trees and rocks, tearing and cutting gorges and cañons from 800 to 1,000 feet deep.) Compare these with rivers of the Atlantic Coast. How are the sand-bars at the mouths of the rivers on the eastern coast to be accounted for? What effect must they have upon commerce? What may we conclude as to the character of Mexican harbors? Would the water-ways afford an enemy means of transportation to the heart of the country? May we conclude that the natural structure of the country affords protection from enemies? What influence has this isolation had upon the progress of the people? Has Mexico a navy? Why not?

Mexico has two seasons—the dry season and the rainy season. The latter begins in June and lasts until October. What is the prevailing wind in each season? What influence has altitude upon climate? Mexico has three zones of climate, according to altitude. The mean temperature of the low lying coast zone or “Hot Lands” is 77 to 82 degrees Fah. at Acapulco on the western coast. What is the climate? (Hot or dry.) What is the climate on the eastern or Gulf coast, where the mean temperature is 77 degrees Fah. rising at Vera Cruz sometimes to 110 degrees Fah.? (Hot, humid and unhealthy. In the rainy season the land is partly under water—steaming. In the dry season the ground is parched and the air oven-like.) What is the character of vegetation, birds, and animals? Compare vegetation with that of cold or cool regions as to appearance, kinds of trees, etc., and its value or usefulness to animals and man. Which city would be the most desirable for a home?

What must be the natural effect of the existing structure and climatic conditions upon the inhabitants of these areas? What kind of houses would they be apt to build? Draw type of houses with environment. The plains rise from the coast gradually to the height of about 2,000 feet where the hills begin, and above these we find other plains.

How does this altitude affect the climate? Vast herds of cattle, horses and sheep roam these plains, and well stocked ranches are in the northern part. Agriculture is the chief occupation in the southern part. The soil being largely volcanic is extremely fertile when irrigated. From the height of 2,000 feet to about 7,000 feet we find the “Temperate Lands.” These combine the conditions of two zones. The heat and moisture of the “Hot Lands” uniting with the cooler breezes of the uplands, produces one of the most equable and delightful climates in the world.

The mean temperature is from 62 to 70 degrees Fah. Compare this with the mean temperature of Chicago. The heaviest annual rainfall recorded is 90 inches. Air-plants and creeping vines are everywhere. Flowers are more delicately fragrant, birds are songsters, and insects are fewer than in the lower hot lands.