Sierra Madre Oriental
SIERRA DE LOS MUERTOS
The belt of closely spaced ridges and valleys south of Monterrey is a series of anticlines formed by the intense folding of rock layers. Differential erosion has removed weaker rock layers and exposed the more-resistant layers, which stand out as prominent ridges. The ridges are near vertical or overturned Lower Cretaceous limestone units. Jurassic and Upper Cretaceous rocks are exposed in the centers of the anticlines.
SIERRA DE MINAS VIEJAS
Like the other mountains of the Sierra Madre Oriental, these anticlinal folds of layered sedimentary rocks formed during the Eocene. The crests of these anticlines have been breached by erosion, exposing cores of gypsum evaporite beds of Jurassic age.
Monterrey, north of Sierra Madre Oriental (in this scene), is the third largest city in Mexico and home to about 3 million people. The growth of the city has been influenced by the rugged mountain topography.
A thrust fault trending roughly northwest-southeast forms the eastern edge of the Sierra de Los Muertos. This fault appears to truncate some of the anticlines.