Portion of the stone test wall at the National Bureau of Standards (now the National Institute of Standards and Technology) in Gaithersburg, Maryland, as it appeared in 1985.
The stone test wall, more than 12 feet high and 37 feet long, is made up of 2,352 stone samples. The wall was originally constructed in 1948 at the NBS site in Washington, D.C. It was moved to its present location in 1977.
By the mid-1980s, some samples, especially sandstones, were beginning to crumble, crack, or flake away. Many limestones developed a surface texture showing fossil fragments.
Photos by I. Peterson