MARBLE TOMBSTONE WEATHERING RATES: A TRANSECT OF THE UNITED STATES

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Abstract
Mean weathering rates measured on marble tombstones appear to vary linearly with mean annual rainfall at locations along the 10°C mean annual isotherm in the United States. Chemically-induced granular weathering is the dominant mechanism. Weathering is most rapid on upper portions of stone faces, which recede at about 1 mm/1,000 yrs where mean annual rainfall is 200 mm/yr, and 16 mm/1,000 yrs when rainfall is 1,000 mm/yr. These rates are about 50% greater than on central inscribed portions of vertical faces and on upward-facing horizontal slabs. Weathering rates of marble tombstones are perhaps one-quarter of those reported for limestone denudation in locations with similar climates and about one-half of the rates on marble tombstones in heavily polluted environments. Preliminary work in a high mountain environment with a mean annual temperature of 2°C indicates that marble weathering rates are an order of magnitude greater than at 10°C, possibly because of frost weathering. Where sprinkler irrigation is used in semiarid localities, tombstones show mechanical spalling, exfoliation, and pitting, and weathering rates are one to two orders of magnitude greater than where sprinkling is not used.