The Rio Grande River was not responsible for the creation of the gorge that slices through New Mexico. The gorge represents a rift in the earth's crust where either side is slowly being pulled away from the other. The rift began forming over 30 million years ago between two fault lines. Around northern New Mexico, the thin sliver of the earth's crust between the two faults slipped downward.
Rivers found their way into the disconnected basins that were formed, filled them with sediment, and eventually joined to form the Rio Grande River that winds its way down the great rift to the ocean. Here in northern New Mexico, you can clearly see the dark brown basalt walls along the river, formed of lava from the mantle - the rift goes all the way down.
New Mexico is a state located in the southwestern region of the United States. Inhabited by Native American populations for many centuries, it has also been part of the Imperial Spanish viceroyalty of New Spain, part of Mexico, and a U.S. territory. Among U.S. states, New Mexico has the highest percentage of Hispanics at 45% (2008 estimate), being descendants of Spanish colonists and recent immigrants from Latin America. It also has the third-highest percentage of Native Americans after Alaska and Oklahoma, and the fifth-highest total number of Native Americans after California, Oklahoma, Arizona, and Texas. The tribes represented in the state consist of mostly Navajo and Pueblo peoples. As a result, the demographics and culture of the state are unique for their strong Spanish, Mexican, and Native American cultural influences. At a population density of 16 per square mile, New Mexico is the sixth most sparsely inhabited U.S. state.[http://en.wikipedia.org/wiki/New_mexico]