Читать книгу Monument Future - Siegfried Siegesmund - Страница 238

In order to make the pXRF measurements of urban varnish, it is obviously necessary to find their occurrences. Some have been found simply by random sighting, but there are more systematic approaches. One factor is the type of stone substrate. Most cases have been found on Triassic red sandstone in the United States, occurring in the Newark Supergroup, which is a geological formation that extends from South Carolina to Massachusetts, as shown in the map in Fig. 4.

Figure 4: Map of Newark Supergroup (Grissom et al. 2018).

Triassic building stone can have different local trade names, for instance, Seneca sandstone in the Washington area and Belleville sandstone from New Jersey in the New York City area, but it is essentially the same rock. Lists of buildings constructed with a specific building stone can be found in state geological surveys reports (Merrill and Matthews 1898), histories of local quarries (Peck 2013), architects’ catalogues raisonnés (Ochsner 1982), and architectural preservation studies (Matero and Teutonico 1982). It may be possible to minimize time in field searching for varnish by doing preliminary viewing of candidate buildings online with images from Google Earth.