Geology of the Central Region of Mexico
In describing the geology of the central area of Mexico, the following limits have been used: to the north, the northern edge of the Neovolcanic axis; to the west and south, the coastlines of the Pacific; and to the east, the shore of the Gulf of Mexico and the Isthmus of Tehuantepec.
The physiographic provinces of the Neovolcanic axis, the Sierra Madre del Sur, and the northern part of the Southern Gulf Coastal Plain are included in this region (see Figure 1.1). In terms of the division of geological provinces used by López-Ramos (1979), the provinces of the Veracruz basin (with the subprovince of Sierra de Juárez), the province of San Andres Tuxtla, the Tlaxiaco basin, the Sierra Madre del Sur, the Altiplano of Oaxaca, the Guerrero-Morelos basin, and the Neovolcanic axis are included.
The climate of the region is highly variable owing to the complex physiography. On the slopes of the Gulf of Mexico the climate changes from humid temperate in high parts of the Sierra Madre Oriental, to semi-hot and humid in the lowlands. On the Pacific slopes the climates vary from hot and subhumid on the southeast flank of the Sierra Madre del Sur and the banks of the Río Balsas to semi-arid, hot, and very hot in the Valley of Oaxaca and the major part of the Balsas basin. In the regions of basins within the Neovolcanic axis, the climate is in general subhumid and varies from temperate to semi-frigid and cold.
In the central Mexico
Figures & Tables
Available knowledge concerning the origin and geologic structure of mexico is still incomplete. Each day scientific discoveries, advances in mapping, and new techniques of exploration offer more information toward the development of tour understanding. Nevertheless, it is still difficult to achieve a complete description of the geologic character of the territory of the nation, as well as to work out functional models to explain the origin of its geologic structure. Along with the development of geologic studies that science has made in mexico, there have been a few attempts to formulate general works covering the many aspects of geology that the country presents. Nevertheless, one must recognize that the lack of information about certain periods in the geological history of the national territory, and the numerous unexplored areas, have constituted some principal obstacles toward achieving a finished work of this type.
Inreviewing past information, it is worth indicating that in 1896 a somewhat unsettled entitled A Sketch of the Geology of Mexico formulated by Jose Guadalupe Aguilera and Ezequiel Ordonez of the Geologic Institute of Mexico, a descriptive work that constituted an important complement to and summary for the Geologic Map of Mexico, which had benn published earlier. Nevertheless, it was not until 1949 that V. Garfias and T.C. Chapin published the work entitled Geology of Mexico, in during the geological history of the republic are included.
A more recent work is The Geology of Mexico, whose author was Ing. Manuel Alvarez, Jr., and which the Faculty of Engineering of UNAM printed as notes