# Timeline of Chacoan history

A timeline of Chacoan history includes Chaco Culture National Historical Park, Aztec Ruins National Monument, Twin Angels Pueblo, Casamero Pueblo, Kin Nizhoni, Pierre's Site, and Halfway House.

## Paleo-Indian Period
### 11000 BC

    First foragers?

## Archaic Period
### 6000 BC-800 BC

    Hunter-gatherers

## 5th century
### 490

    Basketmaker farming begins

## 6th century
### 500

    Turquoise beads and pendants appear; offerings in great kivas (sites 29SJ423, Shabik' eshchee Village)

## 7th century
### 600-800

    La Plata Black-on-White ceramic

### 700

    Population of Chaco Canyon between 100 and 201 people

## 9th century
### 800-900

    Builders use piñon, juniper, and cottonwood trees that grew close by

### 850-925

    Large construction projects.

### 875-1040

    Red Mesa Black-on-White ceramics

## 10th century
### 900-1150

    Large buildings, mounds, roadways, great kivas, and tri-walled structures are built throughout the San Juan Basin.

### 900-1125

    Construction of Penasco Blanco

### 900

    Emergence of the Chaco Anasazi

### 900

    Chetro Ketl pueblo begun

### 900-1025

    Chaco Wash in erosional cycle and cut a paleo-channel.

### 925-1130

    Stable environmental conditions favorable to dry farming throughout the Colorado Plateau. Human populations also stable.

### 950

    Keet Seel, second largest cliff dwelling. is inhabited

### 950

    Nonlocal ponderosa is the dominant beam timber; spruce and fir increase

## 11th century
### 960-1020

    Unpredictable rainfall. Little building at Pueblo Bonito

### 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.

### 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.

### 1030

    Chacoans seek trees at higher altitudes

### 1040

    Increased rainfall

### 1040-1050

    Building resumes at Old Bonito. Pueblo Bonito construction stage II

### 1050-1070

    Pueblo Bonito becomes more complex. Pueblo Bonito construction stage III

### 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.

### 1064, 1066

    Sunset Crater volcanic eruptions; volcanic debris blankets Jemez Mountains and Bandelier area.

### 1080-1100

    Great North Road construction.

### 1080

    Salmon Ruin established.

### 1080

    Construction of Pueblo Alto begins.

### 1090

    Drought

## 12th century
### 1075-1123

    Pueblo Bonito constructed at Chaco.
    Five astronomical observatories are built

### 1100

    Peak of Chaco culture.

### 1100-1104

    Tree felling at Pueblo del Arroyo

### 1106-1125

    Aztec Ruins built.

### 1130

    Pueblo Bonito is four stories tall and contains 800 rooms

### 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.

### 1140–1150

    Collapse of the Ancestral Puebloan culture at Chaco Canyon.

### 1150

    Great Houses empty

### 1180

    Sunset Crater erupts for the second time.

## 16th century
### 1539

    Marcos de Niza erroneously describes the pueblo of Háwikuh as the Seven Cities of Gold.

## 17th century
### 1680-1692

    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".

## 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.

### 1888

    Richard Wetherill and Charlie Mason find the Cliff Palace, Spruce Tree House and Square Tower House.
    Chaco Canyon is surveyed and photographed by Victor and Cosmos Mindeleff of the Bureau of American Ethnology

### 1896

    Richard Wetherill begins excavating Chaco Canyon

### 1896-1899

    George H. Pepper from the American Museum of Natural History leads the Hyde Exploring Expedition in excavating Pueblo Bonito

## 20th century
### 1901

    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 Navajo stonemasons 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.

### 1960

    Floors excavated at Una Vida

### 1971-1982

    The Chaco Project, conducted by the National Park Service and the University of New Mexico, surveys and excavates Chaco Canyon

### 1976-1978

    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 km$^2$) 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.

### 1987

    Chaco Culture National Historical Park is designated a UNESCO World Heritage Site.

## 21st century
### 2001

    Two-thirds of large roof timbers traced to Chuska Mountains and one-third to San Mateo Mountains.