NATIONAL PARK SERVICE Ruins Stabilization in the Southwestern United States Publications in Archeology 10

The records below contain stabilization information for Talus Unit No. 1, a small classic ruin in Chaco Canyon National Monument. They describe a method for stabilizing a distorted, prehistoric stone masonry wall (figs. 120-123).

An interior view of Betatakin Ruin. The three major sites of Navajo National Monument—Betatakin, Keet Seel, and Inscription House—are well protected from the natural elements, except for rare internal disturbances such as blocks of sandstone breaking from cave roofs. The major problems at Navajo are the protection and maintenance of scenic and fragile cliff dwellings, and the control of visitors.

RUINS STABILIZATION RECORD

FIRST SHEET

Chaco Canyon National Monument. Date: July 27, 1959; Ruin: Talus Unit No. 1; Room 27; Wall (N. S. E. W.): NESW. Personnel on job: Joel Shiner and eight Navajos. References to publications and justifications for job: Unpublished notes by Paul Walter in 1933, and Margaret S. Woods in 1934. Their work was accomplished through the School of American Research.

Architecture

Orientation, plan and type (situation, evidence of additional stories, period of construction relative to surrounding rooms, evidence of burning, etc.: Long rectangular room of two stories; masonry is Type II (tiered blocks and spalls). It is one of a half-dozen rooms which are in two rows.

Floor (floor type; additional notes): No floor present now.

Roof (roof type; additional notes): Ceiling of first floor shown by a ledge and by numerous beam holes. Roof of second floor is gone.

Details (notes on doorways, lintels, etc.): Doorways in south wall on first and second stories.

SECOND SHEET

Ruin: Talus Unit No. 1; Date: July 27, 1959; Wall (N. S. E. W.): NSEW.

Condition on date when work started: Ancient masonry: North wall above the ledge leans precariously into the room. East and west walls have eroded and are loose at the top. Footings of all four walls are undercut by erosion. Beam holes are eroding where beams have decayed.

Repair or reconstruction previous to this work: None.

Materials, construction, and technique in making repairs or accomplishing job: Part of the center section of the leaning wall was removed. A horizontal slab of steel-reinforced concrete was poured so as to abut against the junction on the partition walls. Steel rods were fastened through both wall and slab with turnbuckles between. Using the turnbuckles, the wall was pulled back to nearly vertical position. The stones removed were then replaced in tinted cement. East and west walls had already been patched and strongly capped to bear the load. New stones were set in cement around the wall footings. The beam holes were patched in tinted cement.

Date work started: July 29, 1959; Date work finished: August 14, 1959; Work authorized by: Roland Richert, Archeologist.

FIGURE 120. The wall between Rooms 27 and 28, Talus Unit No. 1 was distorted and pushed out of line by pressure of fill, often damp, at left. Arrow shows direction of force. The purpose of the stabilization was to strengthen the wall against the pressure.

FIGURE 121. Plan of reinforced beam to realign and hold north wall, Room 27, Talus Unit No. 1 (not to scale).

FIGURE 122. Construction of concrete beam shown in figure 121. The frame is complete and reinforcing rods are in place. X—X1-beam, Y—location of threaded rods and turnbuckles, Z—temporary braces. The ends of the beam bar against the wall at each side of the bulged area at points where the wall is braced against movement by partition walls. That at the east shown as A.

FIGURE 123. This wall in Talus Unit No. 1 has been pulled back into line; the capping is straightened up. The concrete beam dug into Room 28 is covered and the surface of this room (arrows) is graded to carry surface runoff away from the damaged wall.