Map boundaries: 30 to 40 degrees North; 110 to 120 degrees West

Country (State): Mexico (Baja California, Sonora), United States (Arizona, California, Nevada, Utah).

Part I of the Cultural Landscape

The prehistoric inhabitants of the Sonoran and Mojave Deserts left behind abundant archaeological evidence of their presence. Canals, trincheras sites, and rock art are three of the more notable cultural landscapes in the region.

At the Pueblo Grande Museum and Archaeological Park in Phoenix, the largest canals known from pre-Columbian North America are preserved. Modern irrigated agriculture and suburban development has largely obliterated these canal systems. However, approximately 500 km of major canals and 1600 km of smaller canals have been recorded in the Salt River Valley. These canals were largely built between 900 and 1450 CE. The extensive canal system would easily have diverted all of the available Salt River water during dry periods, suggesting that some sort of coordination or control was necessary to allocate the water among all the systems in the Salt River Valley.

Trincheras sites are distinguished by their locations on a hill or mountain peak and the use of massive stone terraces or walls. At the Cerro de Trincheras site in Sonora, 900 massive stone-walled terraces cover the entire north side of a hill. There was a plaza on the summit and a public events area on the lower slope. Another notable trincheras site is Cerro Prieto 35 miles northwest of Tucson. Numerous small trincheras sites dot Sonora and southern Arizona.

At the Coso Mountains in California, Big and Little Petroglyph Canyons contain the most spectacular petroglyph areas in the western US, with 20,000 designs showing bighorn sheep, deer, antelope. Along the canyon walls are anthropomorphic figures showing dogs attacking sheep and people hunting sheep. Piled rock statues are ‘dummy hunters’ of bighorn sheep.

(to be continued next month)

Ecoregions of the Neararctic Biome in the map area:

302, Sierra Madre Occidental pine-oak forests

503, Arizona Mountains forests

515, Great Basin montane forests

526, Sierra Juarez and San Pedro Martir pine-oak forests

527, Sierra Nevada forests

530, Wasatch and Uinta montane forests

1201, California coastal sage and chaparral

1202, California interior chaparral and woodlands

1203, California montane chaparral and woodlands

1301, Baja California desert

1303, Chihuahuan desert

1304, Colorado Plateau shrublands

1305, Great Basin shrub steppe

1308, Mojave Desesrt

1310, Sonoran Desert

World Heritage Sites

Grand Canyon National Park, Arizona. Terrestrial ecoregions NA503 and NA1304.

Islands and Protected Areas of the Gulf of California (IPAGC). This includes nine protected area units, two of which are within the map area. The two units shown on the map are:

• Islands of the Gulf of California Flora and Fauna Reserve (IGCFFR), Baja California and Sonora. This includes 232 islands, nine of which fall within the map area. Terrestrial ecoregion NA 1310; marine ecoregion 60.
• Upper Gulf of California and Colorado Delta Biosphere Reserve, Baja California and Sonora. Includes the former outlet off the Colorado River. Terrestrial ecoregion NA1310; marine ecoregion 60.

Yosemite National Park, California. The Ahwahnee resort hotel, Leconte Lodge, and Ranger’s Club in Yosemite Valley and the Wawona Hotel and Thomas Hill Studio in Wawona are National Historic Landmarks. Ecoregion NA527.