Preliminary Report on Examination of Column Capitals at the Jefferson Memorial, Washington, D.C.

McGee, Elaine; Woodruff, Mary

An examination is being made of the column capital volutes at the Jefferson Memorial in Washington, D.C. by Elaine McGee and Mary Woodruff, from the U.S. Geological Survey. The intent is to see if features can be identified that would explain why some of the volutes have cracked and failed. Access from scaffolding being used for the stone survey at the Memorial has permitted close examination of the stone and aided our recognition of cracks and identification of features that might explain their presence. To date, 126 of the 216 volutes at the Memorial have been examined. So far, we have examined five of the volutes from which pieces fell or were removed in 1990. The fracture faces on the broken volutes are nearly identical to the fracture faces on the pieces that were removed. The absence of an inclusion rich zone on these fracture faces supports our earlier interpretation that while inclusion phases may contribute to a weakness in the stone, they are not likely to be the sole cause of the failure of the volutes. Cracks and indentations in the marble have been identified on a number of volutes, particularly on the outward facing volutes that are directly exposed to wind and rain. We group the flaws identified on the volutes by location on the volute and by apparent severity. Thirty two volutes from nineteen columns have cracks that are open and (or) appear extensive. Although we have identified a number of linear openings in the lower half of the volutes that are in the general location of the fracture plane on the broken volutes, none of these pieces is loose or appears in danger of immediate failure. Cracks may be associated with inclusion traces in the marble, however, a significant number of cracks are not associated with inclusions. These cracks appear to have developed along horizontal planes in the marble that coincide with changes in texture in the marble. The areas where grains and texture changes occur may be indicative of a weakness in the marble that is a remnant from the formation of the marble. These planes of weakness appear to extend through the single blocks of marble that form a given column capital. Generally, if one volute is cracked or missing on a column capital, the others are likely to have some cracks in a similar location. Although zones of grain or texture changes can be identified on exposed volutes, at this point they are very difficult to recognize on volutes that retain some surface polish or on volutes that have developed surficial accumulation of dirt and alteration crusts. Zones of grain or texture changes are associated with cracks, but not all areas of visible texture changes have developed cracks. This suggests that some external factor (like moisture penetration or vibration) takes advantage of the weakness in the marble to develop the cracks.

Preliminary Report on Examination of Column Capitals at the Jefferson Memorial, Washington, D.C.

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