Sierra Madre Occidental

The Sierra Madre Occidental (Spanish for "Western part of the Mother Range") is a mountain range. It is in Mexico.
The Sierra Madre Occidental is about 780 miles long (1250 km). It runs along the Gulf of California. It goes from Sonora in the north to the Sierra Madre del Sur in the South.
These mountains have deserts nearer to sea level and oak forests further up. Because there are many deep river valleys, the mountains affect the rain. There are many places where the air is very wet. That means many different kinds of plants and animals can live in the Sierra Madre Occidental. Scientists call this biodiversity.