Geology of the Northern and Northeastern Regions of Mexico
For description of the northern and northeastern regions of Mexico, one can use the following natural limits: to the west, the Sierra Madre Occidental; to the east, the Gulf of Mexico coast; and to the south, the northern edge of the Neovolcanic axis.
The region comprises, according to the physiographic division of the DGG (see Figure 1.1), the provinces of Sierras and Plains of the North (Basin and Range), the Sierra Madre Oriental, the Great Plain of North America, the Central Mesa, and the Coastal Plain of the northern Gulf of Mexico. Nevertheless, the division that is used is based fundamentally on the paleogeographical elements of the Mesozoic in this part of Mexico. In various forms, these elements have a general correspondence with the physiographic provinces mentioned above, chiefly in the origin of orographic forms that are particular expressions of the types of geological phenomena that generate them.
The climate of all the region varies in general from hot to temperate, and regular summer rains occur. Additionally, precipitation records reveal that the climates vary from dry to semi-arid in the west of this zone and from humid to subhumid in the Sierra Madre Oriental and the Coastal Plain of the northern Gulf of Mexico.
The area of the State of Chihuahua is characterized, particularly in its eastern part, by the presence of folded mountains formed from marine Mesozoic strata. These mountains make up prominent topographic peaks that occur separated by great plains that were elevated as they were filled. These
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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