A mixture of clay and water called adobe was one of the primary building materials used by American Indians of pre-Inca Peru, Mesoamerica, and the North American Southwest of what is now the United States. Applied wet as plaster or mortar, or mixed with plant fiber and dried into bricks, adobe enabled builders to construct vast APARTMENT COMPLEXES, referred to as pueblos by the Spaniards, throughout these regions.
The Moche, who lived on the northwest coast of what is now Peru from about 200 B.C. to A.D. 600, built enormous temples using adobe bricks. One of the most impressive examples of Moche adobe construction is the larger of two pyramids built at Moche near the modern city of Trujillo. The largest of these pyramids, the Huaca del Sol, consists of about 130 million bricks. These bricks are inscribed with what archaeologists believe are the names of individual workers or teams of workers. Archaeologists have found a number of smaller adobe pyramids as well as adobe forts scattered throughout what is now Peru. Often these structures were decorated with clay relief and painted with murals. The Hohokam, whose culture arose in what is now Arizona in about 300 B.C. and who are the ancestors of the Akimel O’odham (Pima) and Tohono O’odham (Papago), built massive mud-walled structures that Spanish conquistadores compared to castles. One of the foremost examples of Hohokam architecture, Casa Grande, is located outside of what is now Phoenix, Arizona. Thought to have been built about A.D. 1300, Casa Grande is four stories tall, and at least 1,500 cubic yards of soil was used in its construction. It has adobe walls that are more than four feet thick at their base, tapering to about two feet at the top, with no reinforcing beams. Casa Grande’s ceilings were framed with more than 600 juniper, pine, and fir beams cut from mountains more than 50 miles away. The Hohokam often used I-beam construction for such framing. Archaeologists do not know the exact purpose of Casa Grande and other huge Hohokam buildings but believe that they were designed to protect against attack. Window openings in upper levels of Casa Grande are aligned to the position of the sun at the time of equinox and at solstices, so they might have served as OBSERVATORIES as well.
Initially archaeologists speculated that Casa Grande’s thick walls were built in stages, with mud packed into wattle and daub forms made from woven branches plastered with mud, and then compacted by applying pressure. However, recent study has shown that Hohokam builders mixed mud to the proper consistency in large holes they dug in the ground, then piled it up, or “puddled” it, by hand in 26-inch courses. Each layer was allowed to dry before the next one was laid. The process was repeated layer by layer. After nearly 700 years, the walls of Casa Grande are weathered, but they still stand. Their durability can be credited to the fact that the original ARCHITECTS selected caliche for the adobe. Caliche is a soil layer in which earth particles have been bonded by carbonates of calcium or magnesium, which cause the adobe to harden, almost like cement, as it dries.
In addition to the Hohokam, the Anasazi—who lived in the Southwest of what is now the United States from 350 B.C. to about A.D. 1450, and who are the forerunners of modern Pueblo people—relied on adobe for the construction of their homes. In about A.D. 700 they traded the pit houses that they had previously occupied for above-ground cubicle homes, built so that adjoining units shared walls. As their population grew, the Anasazi added stories to their dwellings. Families slept in the upper front units, where they would be warmed at night by a form of passive solar heating provided by the adobe. Heat absorbed from the sun by the adobe walls throughout the day radiated into the rooms at night. Food was stored in the cooler interior rooms.
The most skilled Anasazi adobe builders lived in the pueblos of Chaco Canyon in what is now New Mexico. According to the National Park Service, the agency in charge of the site, buildings in the Chaco community were originally constructed in A.D. 700 from a central design that was added onto later. That, combined with the construction techniques used to build the structures, has led archaeologists to believe that the Anasazi had architects whose job it was to plan the structures before they were built.
In Pueblo Bonito, the main complex in Chaco Canyon, an average room required about 50,000 tons of stone and 16,500 tons of clay for its construction. The adobe walls were built on top of mortar- and rubble-filled trenches in order to keep the walls from settling. The walls themselves, which tapered from three feet at the base to one foot at the top, were made of rough, flat stones mortared with adobe. This core was covered with flat pieces of rock called ashlar. A layer of adobe was plastered over this. When the building was expanded, Anasazi builders bonded new walls to old ones by interlocking the new stones with those in the existing walls. Some of the walls in the Chaco complex had a rubble and adobe core and were faced with stone.
The Anasazi builders who lived in areas along the Rio Grande River often could not find enough suitable rock for construction of their homes. There was, however, an abundance of water. Instead of using adobe as plaster over a rock core, they made fat adobe bricks called “turtle backs,” slapping and shaping them, then setting them atop each other and smoothing over the surface with a finish coat of adobe. Often historians mistakenly credit the Spaniards with teaching the Pueblo people how to make uniform adobe bricks that are molded in forms. (The Spanish learned adobe construction from the Moors, who migrated from Africa to Spain in A.D. 711.) Two archaeological sites that have been dated to about A.D. 1300 show evidence that precontact American Indians poured wet mud into stone or wooden forms and allowed it to sun-dry. These sites are the pre-Hopi site of Homol’ovi and the Fourmile Ruin near Taylor, Arizona. The most famous of the adobe pueblos still occupied today is Taos Pueblo in New Mexico, which was started before the 1500s. The walls of the two clusters of units that make up this pueblo are two feet thick at the bottom tapering to about a foot thick at the top. Each spring the pueblo’s residents replaster the exterior walls of their homes with a new coat of adobe. Adobe is also used as a roofing material at Taos and in other pueblos. Cedar beams, whose ends protrude through the walls, support the roofs. Branches are placed on these log beams, or vigas, and are next covered with grass. A layer of adobe plaster serves as a sealant.
Today adobe architecture has come to be known as one component of the Santa Fe style and is popular throughout the Southwest. However, modern builders, who must meet mandated building codes, find it more expensive to build with adobe than to construct frame houses and plaster the exteriors with adobe to make them look authentic.
Tidak ada komentar:
Posting Komentar