Only when we come to the Mississippi in the northern continent and the Rio de la Plata in the southern do we find a pair of rivers which correspond to any degree in the character of the life surrounding them, as well as in their physiographic character. Yet even here there is a vast difference, especially in the upper courses of the river. Each at its mouth flows through a rich, fertile plain occupied by a progressive, prosperous people. But the Rio de la Plata takes its rise in one of the world's most backward plains, the home of uncivilized Indians, heartless rubber adventurers, and the most rapacious of officials. Not infrequently, the degenerate white men of these regions, yielding to the subtle and insidious influence of the tropics, inflict the most outrageous abuses upon the natives, and even kill them on slight provocation. The natives in turn hate their oppressors, and when the chance comes betray them or leave them to perish in sickness and misery. The upper Mississippi, on the other hand, comes from a plain where agriculture is carried on with more labor-saving devices than are found anywhere else in the world. There States like Wisconsin and Minnesota stand in the forefront of educational and social progress. The contrasts between the corresponding rivers of the two Americas are typical of the contrasts in the history of the two continents. CHAPTER III. THE GEOGRAPHIC PROVINCES OF NORTH AMERICA The four great physical divisions of North America--the Laurentian highland, the Appalachian highland, the plains, and the western cordillera--are strikingly different in form and structure. The Laurentian highland presents a monotonous waste of rough hills, irregular valleys, picturesque lakes, and crooked rivers. Most of it is thinly clothed with pine trees and bushes such as the blueberry and huckleberry. Yet everywhere the ancient rock crops out. No one can travel there without becoming tiresomely familiar with fine-grained, shattered schists, coarse granites, and their curiously banded relatives, the gneisses. This rocky highland stretches from a little north of the St. Lawrence River to Hudson Bay, around which it laps in the form of a V, and so is known as the Archaean V or shield.