EN:

The morphology of the Québec region and the lower St. Lawrence valley is reappraised in this article divided in three parts. The physical landscape is described in part I ; the structural conditions are examined in part II and the morphological problems are presented in part III.

The relief is the result of a succession of glacial episodes and submersion and emersion episodes which followed glaciation. The over deepening of the Limoilou depression and the opening of Calvaire lake and Cap Rouge depressions are the results of the glacier. To the submerged phase correspond the alluvial fill, especially thick in the Limoilou depression, and during the emersion phase, the St. Lawrence cut in soft schists the Ancienne Lorette and the lower terrace which would have been shaped after the over deepening of the Limoilou depression.

EN:

This is a systematic study of karsts in Eastern Canada especially caves and underground streams. The analysis of the limestone content in the water bas been used to study the actual dissolution of limestone. It bas been deducted that some of the most typical caves, such as the Saint-Casimir cave in Portneuf county, was formed 3,500-4,000 years ago. This dating is cross-examined with other factors supplied by the physical geography of the area : ice retreat, study of pollens, C.14 analysis, post-glacial surrection, etc.

The evolution of the limestone coast of the Mingan-Anticosti area is also described. Everywhere, in the Mingan area and the Anticosti region as well as in the Saint-Casimir cave, the erosion is very rapid. It is a constant fact in regions with heavy snowfalls as demonstrated in similar regions of Norway and Alaska.

The climatic influence on the shape and speed of karstification is a determinant factor.

EN:

Spruce budworm bas invaded the forest of Québec since 1939, especially the pines of the coniferous area. There are jour major infested regions : three are located on the North shore of the St. Lawrence river : in the Gatineau river bassin, in the Laurentians between the Lachute Area and lake St. John, and in the North Shore region behind Baie Comeau Sept-Iles. The fourth region starts behind Rimouski and spreads eastward, covering the whole Gaspé peninsula. In this last the authorities are quite concerned about this plague, which is becoming a serious menace to the forest industries. Various air-spays have been used during the past jour years in order to circumscribe the dammages, and more than 4,000,000 acres have been treated with DDT, first step toward the rehabilitation of the forest.

EN:

Despite the fact that Brazil is a young and vast country, some of its regions have already acquired a personality of their own. The Sertâo in the Northeast is such a case. Of triangular shape, the Sertâo opens in the North, towards the Atlantic ocean ; it covers 10% of the total area of Brazil and include more than 90% of the states of Rio Grande do Norte, Ceara and Paraiba.

It is a semi arid region with a dry climate, chiefly responsible for an original type of vegetation : the caatinga. The fundamental features of the relief are horizontal with depressions and inselbergs. The rare good soils are deteriorated and the hydrographic network is fair.

Such a severe country is inhabitated by 7 millions persons of mixed ethnic origins. The dominant occupational types, are the vaqueiro, the garimpeiro, the truck driver , and, during the dry season, the flagellado. It is an « under-developped » country economically , with low standards of living, and a production based on food and cattle. If the Sertao is unsafe foreigners, it remains for the natives, a mystical and attractive country that may become more prosperous with the hydro-electric development of the Sao Francisco River.