Assessing Weathering of Vertical and Horizontal Limestone Tombstones in Washington State

Author(s)

Mary Powers

Faculty Mentor(s)

Lisa Ely (Geological Sciences)

Abstract

Rain, wind, and other processes modify Earth’s landscape and rock material over time. Examining tombstone weathering is a way to measure the weathering rates of rock. The date listed on the tombstone provides the approximate year that weathering started. The limestone tombstones examined in this study are especially susceptible to chemical weathering by acid rain, which is created by fossil fuel combustion. While some might think tombstones are a permanent reminder of their loved ones, over the years they can become difficult to read due to the weathering processes. To discover which tombstones show more weathering, vertically oriented tombstones and horizontally oriented tombstones were examined from multiple graveyards using a visual weathering classification system. A total of five cemeteries were visited in Yakima, Ellensburg, Leavenworth in central Washington, and Black Diamond in western Washington. The goal was to sample 500-1000 tombstones older than the year AD 1930 within these cemeteries. I hypothesized that vertically oriented tombstones would show more weathering than horizontally oriented tombstones, because vertical tombstones are more exposed to wind whereas horizontal tombstones are protected from wind. However, preliminary findings suggest that horizontal tombstones show more evidence of weathering than vertical tombstones. A contributing factor to this observation could be that moisture stands on horizontal tombstones for longer periods, allowing more time for the chemical weathering reaction. By sampling from both central Washington and western Washington one can gain an understanding as to whether acid rain weathering is more prevalent in wetter or dryer climates.

Keywords: Geomorphology, Weathering, Limestone

Presentation

3 thoughts on “Assessing Weathering of Vertical and Horizontal Limestone Tombstones in Washington State”

  1. I wonder if the reason Tacoma is an outlier might be due to the cemeteries proximity to a large city which also functions as a port. The fossil fuel usage would be significantly higher there. Could that be enough to weather vertical and horizontal at nearly the same rates?

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