BOLETÍN DE LA SOCIEDAD GEOLÓGICA MEXICANA
TOMO LIX, NÚM. 1, 2007, P. 1-7
The First Geologic Map of Sonora
Instituto de Geología, Universidad Nacional Autónoma de México, Estación Regional del Noroeste,
Apartado Postal 1039, C. P. 83000 Hermosillo, Sonora, México
The 1888 publication by José Guadalupe Aguilera Serrano about the 3 May 1887 Sonora, Mexico earthquake contains the earliest geologic map of Sonora, a 1:1,000,000 scale color map with six cartographic units, reproduced in this paper.
On the map, which covers ~20,000 km2 of northeastern Sonora, and in the accompanying article, Aguilera delimited and described parts of what is now known as the Jaralito and Oposura batholiths and assigned them, remarkably, an Eocene age.
The map unit of volcanic rocks belongs mostly to the vast cover of the middle Tertiary Sierra Madre Occidental volcanic province and the units of Pliocene and Quaternary rocks to the fi ll of extensional basins.
Aguilera assigned a Quaternary age to the basalt fl ows in the Moctezuma and San Bernardino valleys, which he described as covering the alluvium of these valleys.
The rocks of the Pliocene map unit were described by Aguilera as an indurated conglomerate dipping 20° S, overlain with angular unconformity by alluvium, and most of its clasts being of volcanic origin; this unit is now known as the Báucarit Formation of Miocene age.
The Cretaceous map unit, described by Aguilera as ash grey, compact, and fossiliferous limestone beds belonging very probably to the Comanche series, is now known as the Lower Cretaceous Mural Limestone.
Aguilera’s map covers a series of north-south trending mountain ranges separated by the Moctezuma, Bavispe, San
Bernardino, Fronteras, and Agua Prieta River valleys, a landscape pattern typical of the Basin and Range physiographic province.
Aguilera described this transition zone between the plateau of the Sierra Madre Occidental in the east and the lowlands in the west as a large-scale staircase pattern, with the steep, fault-bounded side of the mountain ranges always facing west.
A rare photograph by Camillus S. Fly possibly shows Aguilera and his fi eld party near Bavispe, Sonora in August 1887.
Key words: José Guadalupe Aguilera Serrano [1857-1941], history of geology, geologic map, Sonora, Mexico, Basin and Range province, Sonoran batholith
La publicación en 1888 por José Guadalupe Aguilera Serrano sobre el terremoto del 3 de mayo de 1887 de Sonora incluye la primera carta geológica de Sonora.
Se trata de un mapa en color a escala 1:1,000,000 con seis unidades cartográfi cas, el cual es reproducido
en este trabajo.