San Juan Basin
Archaeological Society

A Colorado Nonprofit Corporation
Lewis Mill

The San Juan Basin Archaeological Society... exploring, learning about, and preserving
archaeological, cultural, and historical resources in the Four Corners region since 1979.


About us


Field Trip and Activity Schedule

Moki Messenger Newsletters

Volunteer Opportunities

PAAC Classes


Reading List and Helpful Links

John W. Sanders Internship Fund

Field Trip Archives

Club Business

Contact us

One of the SJBAS objectives is for members to learn about the archaeology and early history of the Four Corners region. Presentations at our monthly meetings and PAAC classes presented by History Colorado are a wonderful way to acquire more in-depth knowledge. Our Reading List includes a number of books that cover the archaeology and early history of the Four Corners region. Our monthly newsletter, the Moki Messenger, often includes educational articles, and our Links web page includes links to many educational organizations and resources. This web page contains links to various resources on the Internet that offer excellent information and insight.

Below is a basic introduction to the culural history of the Four Corners region presented in the Pecos Classification phase sequence. Click on the hyperlinks in blue for more information.

Phase Sequence Time Period Cultural Summary
Paleo-Indian Period 10,000 - 5,500 BC Small bands of hunters relying on large, now extinct, Pleistocene megafauna. Three complexes based on time sequence: Clovis, Folsom, Plano
Archaic Period 5,500 BC - 1,200 BC Extinction of earlier Pleistocene fauna; small hunting and gathering groups; widespread use of wild plant resources
Early Basketmaker II 1,200 BC - 50 AD Lived in the open or in caves; nomadic lifestyle but first cultivation of maize
Late Basketmaker II 50 - 500 AD First successful agricultural populations; sedentary settlement pattern; shallow pit structures; extensive storage features
Basketmaker III 500 - 750 AD Widespread adoption of domesticated crops: maize, squash, and beans; pithouses, pottery, and introduction of bow-and-arrow. 
Pueblo I 750 - 900 AD Increase in number of sites and average site size, the appearance of above-ground jacal and stone architecture alongside semi-subterranean pithouse structures, and larger storage facilities. So-called “proto-kivas” first make their appearance
Pueblo II 900 - 1,150 AD Further increase in the number of sites and site size, a shift toward above-ground coursed masonry architecture, larger numbers and larger sizes of storage facilities, and formal kivas. Sites typically contain between 6 and 9 rooms, with increasingly complex architecture, multistory construction; Chaco phenomenon flourishes
Pueblo III 1,150 - 1,350 AD Aggregation of populations into progressively larger centers, gradual collapse of the Chaco phenomenon;  realignment of social structures toward Mesa Verde and Aztec; dramatically redued rainfall; site abandonment toward end of the period
Pueblo IV 1,350 - 1,600 AD Significant movement of people into river valleys for more reliable water, especially along the Rio Grande, Rio San Jose, and Zuni River. Most sites are small, but some of the largest contain over 500 rooms.
Pueblo V 1,600 - Present Post European contact

Links to Various Educational Resources


Colorado Archaeological Society (CAS)

Crow Canyon Archaeological Center - Peoples of the Mesa Verde Region

History Colorado - sponsor of PAAC classes

All about PAAC - Program for Avocational Archaeological Certification

Center of Southwest Studies - Fort Lewis College

Mesa Verde - Ancestral Puebloans and their World

Ancestral Puebloan dwellings in Colorado

Chimney Rock National Monument - In Depth Info

University of Colorado Boulder - Mahaffy Cache - 13,000-year-old stone tool cache from the Clovis culture

Colorado Archaeological Society - Publications - Southwestern Lore

Archaeological Conservancy - blog by Dr. Jim Judge - The Archaeology of Puzzle House: Preservation and Excavation (in the Great Sage Plain near Cortez)


Archaeology of the Barrier Canyon style rock art in Horseshoe Canyon in Canyonlands National Park

The Cedar Mesa Project

Archaeology of Natural Bridges National Monument

Examination of the Prehistoric Sandal Collection of Natural Bridges National Monument

Edge of the Cedars Museum in Blanding - Interactive exhibit of Ancestral Puebloan pottery - Wow!


History of Navajo National Monument - including Betatakin and Keet Seel