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“The Pajarito Plateau and Los Alamos”

Southwest Crossroads Spotlight

Millions of years ago the Jemez Mountains were formed by volcanic flows. Later eruptions of ash tuff, carved by wind and water, formed the Pajarito [Little Bird] Plateau on the east flank of the Jemez Mountains. The Rio Grande, flowing south through central New Mexico, cut a deep channel through the basalt cliffs on the southern portion of the plateau where the 1.5 mile-high city of Los Alamos is now located.

Sometime between 1175 and 1250 AD the first Indians arrived on the Pajarito Plateau. They came from present-day Arizona along the Little Colorado River. Archeologists believe they were ancestors of the Cochiti and other Keresan-speaking peoples living in pueblos to the south and west. Some of these settlers built homes of volcanic tuff where three or four families lived together in as many as twenty rooms. Some lived apart from other groups in caves in the canyon walls. Until a great drought struck the Southwest between 1276 and 1299, the Keres people were able to grow crops on the mesa tops of the Plateau.

Aerial View of  Chetro Ketl in Chaco Canyon“Aerial View of Chetro Ketl in Chaco Canyon,” Tom Baker (Photographer)You’ll need 3-D glasses to view this Anaglyph image. Don’t have a pair? Request 3-D glasses right away!

A second wave of Indian peoples moved to the Plateau around 1300. These people spoke Tewa and came from Mesa Verde in Colorado and Chaco Canyon in New Mexico. Besides cliff houses in the canyon walls, they built large community dwellings of hundreds of rooms on top of the mesa. Probably they built their pueblos high on the plateau as a defense against raiding Navajos and Utes. At the pueblo of Tsirege, Pajarito residents built a wall about 150 feet long to ward off surprise attacks from the west.

Within fifty years of their arrival, the Tewas started to drift away. Stories tell the people of Santa Clara and San Ildefonso Pueblos that their ancestors were forced off the plateau by drought and Indian raids. Scientific measurements show that a drop in the average annual temperature during those years shortened the growing season. This meant that the Indians were unable to grow corn, their major food crop.

When Spanish expeditions [entradas] came to the area in the mid-sixteenth century, they chose to stay near the Rio Grande and its tributaries. As far as we know, the Spaniards didn’t venture onto the cliffs of the Parajito Plateau. But later colonists did, and during the eighteenth century some newcomers challenged San Ildefonso for its land through Spanish land grants. By the time the Atchison, Topeka and Santa Fe Railroad reached Santa Fe, Anglos acquired the lands of the Pajarito Plateau through land grant battles and purchase.

The railroad brought surveyors, homesteaders and cattle ranchers to the area. Spanish and Anglo-Americans built homesteads on the mesa tops. In 1917, Ashley Pond founded an exclusive school for boys with health problems on the Pajarito Plateau. The Los Alamos Ranch School was a model of disciplined study and outdoor sports for 25 years.

In November of 1942 the government notified the school that it would take over its facilities under the War Powers Act. Soon after, the U.S. Army began to transform the area into a top secret army post under the command of General Leslie Groves. Selected largely for its geographic isolation, Los Alamos became the secret site where physicists and technicians built the first atomic bomb.

General Groves appointed J. Robert Oppenheimer as Project Director of the Los Alamos Laboratory and the Manhattan Project. Oppenheimer selected top scientists to work on the project. For over two years they worked under tight security. The bomb was tested at Trinity Site near Los Alamos on July 16, 1945; the explosion equaled 20,000 tons of TNT. On August 6, 1945, the U.S. dropped the first atomic bomb (code name “Fat Man”) on the city of Hiroshima in Japan. Three days later, they dropped the second (code name “Little Boy”) on Nagasaki. The Japanese surrendered. The Second World War came to a close and the Nuclear Age was ushered in.

At its peak during the war years, over 4,000 people lived and worked in the secret city. After World War II, many scientists and maintenance workers moved on. Others stayed, drawn by the spectacular landscape, the human community, and ongoing jobs at the Los Alamos Laboratories. Today, the city of Los Alamos still revolves around these aspects. Some of the scientific research and development projects underway at the Los Alamos Laboratories involve the production of plutonium and other weapons work.