Unpredictable rainfall. Little building at Pueblo Bonito [1]
1000
"Chaco phenomenon" acceleration of cultural development
1000-1075
Great House construction, and roads expanded. The first usage of chocolate further than central Mexico was first used in ceramic cylinders for rituals.[6]
1000-1140
Escavada Black-on-White ceramics
1025-1090
Depositional period during which time the paleo-channel was filling. There is some historical, anecdotal evidence that the inhabitants of Chaco Canyon may have constructed a dam at the west end of the canyon.[4]
Building resumes at Old Bonito. Pueblo Bonito construction stage II [1]
1050-1070
Pueblo Bonito becomes more complex. Pueblo Bonito construction stage III [1]
1050
Imports of copper bells, Macaws, and shells (origin unknown)
1054
~July 4 - Cliff painting near Penasco Blanco consisting of three symbols: a large star, a crescent moon, and a handprint, may portray the sighting of SN 1054, the Crab Nebula supernova.[7]
Pueblo Bonito is four stories tall and contains 800 rooms [9]
1130-1180
Fifty-year drought in the Southwest. Rain and snow cease to fall. Alluvial groundwater declines, floodplain erosion occurs. Dry-farming zone reduced, crop production potential decreased. Severe arroyo cutting and depression of alluvial groundwater. Severe environmental stress.[5]
1140–1150
Collapse of the Ancestral Puebloan culture at Chaco Canyon.
The Pueblo Revolt of the Pueblo people against Spanish colonists in the New Spain province.
1774
Don Bernardo de Miera y Pacheco identifies the Chaco Canyon area as "Chaca" on a map. The term, a Spanish translation of a Navajo word, is thought to be the origin for "Chacra Mesa" and "Chaco".
18th century
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19th century
1844
Josiah Gregg refers to the Chaco pueblos in his book Commerce of the Prairies, making its first appearance in popular culture.
1849
Lt. James H. Simpson leads the Washington Expedition, a military reconnaissance team which surveys Navajo lands and records cultural sites in Chaco Canyon. Illustrations created by the Kern brothers are included in a government report.
1877
Artist and photographer William Henry Jackson participates in the Hayden Survey of the Western United States, producing maps of Chaco Canyon, but no photographs due to technical problems.
General Land Office special agent S. J. Holsinger recommends creating a national park to preserve archaeological sites in Chaco Canyon
1907
Chaco Canyon National Monument is established.
1928-1929
American astronomer and University of Arizona professor A. E. Douglass participates in a National Geographic Society research project exploring Chaco Canyon. Using his newly invented technique of dendrochronology, Douglass dates Chetro Ketl and dozens of Chacoan sites
Expedition under Neil Merton Judd to collect dendrochronological specimens to date habitation of Chaco Canyon
1937
A Civilian Conservation Corps of Navajostonemasons repairs Chacoan buildings in Chaco Canyon. A previous group built soil conservation devices, planted trees, and improved roads and trails.
1941
Heavy rains cause Threatening Rock to fall, destroying ~60 rooms at Pueblo Bonito.
Fourteen rooms at Pueblo Alto excavated by the Chaco Project
1980
Chaco Canyon National Monument is renamed Chaco Culture National Historical Park with 13,000 acres (53 km2) added. The Chaco Culture Archaeological Protection Site program is created to protect Chacoan sites.
1982
NASA's Thermal Infrared Multispectral Scanner (TIMS) detects over 200 miles of a prehistoric (AD 900 or 1000) road system in Chaco Canyon, as well as walls, buildings, and agricultural fields.
1983
Dean and Warren estimate 200,000 trees were used to build great houses.
^Kohler, Timothy A. Sebastian, Lynne. (July 1996). "Population aggregation in the prehistoric North American Southwest." American Antiquity v61.n3 : pp597(6).
^ abDurand, Stephen R. (Jan 2004). "Relation of "Bonito" Paleo-channels and Base-level Variations to Anasazi Occupation, Chaco Canyon, New Mexico." American Antiquity 69.1: 191(1).
^ abJorgensen, Joseph G. (Winter 2005). "Archaeological sociology in America's Southwest". Journal of the Southwest 47.4: 637(28).