Weathering Rates of Portland Arkose Tombstones

Old cemeteries offer fertile ground for studies in weathering rates of stone materials. Portland arkose, a Triassic sandstone, was widely used in central Connecticut as a material for gravestones during the 18th and 19th centuries. The depth of inscription on these stones was used to measure the extent of weathering. Examination indicates that the tombstones have been weathering at an average rate greater than 2/64th inch over a 145-year period but that there has been a three-fold increase in the rate of weathering since the turn of the century. Weather information suggests an increase in the annual temperature since 1900 which, along with the increase in CO2 content of the atmosphere, is probably responsible for the increase in rate.