This is a partially developed activity description. It is included in the collection because it contains ideas useful for teaching even though it is incomplete.
Sourcing architectural bricks by chemical analysis as an analog for sourcing magmas
Wayne PowellBrooklyn College
Topic: geoarchaeology, geochemistry, source of magmas
Course Type:intro upper level
Description
Using geochemical indices/discrimination diagrams to constrain the origin of the magma for igneous rocks isn't particularly interesting to most students, because the problem is pretty far removed from what they find interesting and relevant. The same kind of geochemical analyses and discrimination diagrams can be used, however, to tackle the likely sources of some kinds of archaeological materials. In New York City, yellow brick from the 17th and 18th centuries is a distinctive brick of uncertain origin. Our experience with students on urban field trips is that they are curious about where the yellow brick comes from and what makes it different from the more common red brick in older buildings in the city. Was it made with a local clay? Was it brought by the Dutch as ship ballast? If the latter, was it brought from Holland? the Dutch colonies in the West Indies? Allan Gilbert (geoarchaeologist at Fordham University) has extensive analytical data on New York City bricks and the geochemistry of potential source materials that can be used to build an exercise for students to solve the source problem. Similar data might be available locally in other cities.
Once students have learned how to use geochemical data for a problem that interests them, one could draw an analogy with similar chemical fingerprinting that can be done with igneous rocks.
Goals
-students plot and interpret geochemical data and use discrimination diagrams to determine the source of materials.
-students gain experience with the relevance of geology to solving non-geologic problems.
Assessment
-depends on the style of assignment