Sierra Madre Occidental
The Sierra Madre Occidental is a mountain range in western Mexico. The name Sierra Madre means ""Mother Mountains"". The range extends from near the Arizona border down to the Sierra Madre del Sur. The high plateau that is formed by the range is cut by deep river valleys. This plateau is formed from volcanic rock overlying a basement of metamorphic rock.This uplift has caused changes in weather patterns; increased rainfall occurring in the mountains has provided areas where ecosystems can form in wetter areas than surrounding land. This water-source forms watersheds that provide the arid surroundings with water that makes it possible to irrigate and farm crops. The wet ecosystems are islands of biodiversity, differing significantly from what would otherwise be a desert landscape. Oak forests are the predominant plant life and extend into the low land deserts.This forest and canyon land provided a place for a variety of indigenous people to live, until Spanish settlers with associated Mestizos came into the area to found towns for the silver mines in the area. The major industries in the area now are agriculture and forestry, which have become contentious because of land degradation and the native population's opposition to these practices.