Building-Stone Geology

Goals

• Learn to recognize various rock and mineral types
• Understand the relationship between the physical properties of a rock and its practical usefulness in a building context
• Appreciate the diversity of rocks, even in your own downtown

Skills

• Perform acid and hardness tests
• Sketch and photograph the chosen rock type
• Identify minerals in the rock
• Writing a clear report on the practical properties of rocks
• Giving an informative oral presentation

This is a great lab for a class in an urban setting with no means to leave the city. There are also many parts of the world (like Florida) where the geologic setting is simply a little limited.

In part because of the paper, this is a multi-part lab. Reserve at least one lab period for the initial visit to the site and tests, another for the walking tour, and a third for the oral presentation, with a little time in between for library research and writing.

The first step is for the students to choose building sites and be introduced to building owners. The students are told to take the perspective of an impartial geologist consulted by the building owner to advise on the best rock type for a given job. They will be examining the rock type currently in use and comparing it to three others. Once they have permission from the owners, the students will perform test (hardness, acid, and visual) to identify the rock type (something they have learned to do earlier in the term). They will be provided with thin sections and hand samples of the same rock type and will perform mineralogical analyses on them.

Two thirds of the way through the term, the class goes on a walking tour of the downtown area with a stop at each student's building site. Each student gives a brief summary of their findings about their rock type when the class arrives at their site. At the end of term, each student turns in a paper describing their rock type, comparing to others, and making a final recommendation, and gives a brief presentation describing their rock type.

There are two graded components for this project:

• Written report: intended to persuade a client (educated, but not a geologist) whether or not to build with a particular sort of stone and made up of four elements:
  1. Description of the current building stone: its mineralogy, geologic history, probable origin (quarry), and other uses for that rock type
  2. Descriptions of three other building stone types
  3. Comparison between the current building stone and the three others described, emphasizing advantages & disadvantages
  4. Conclusion recommending one of the four stones
• Oral report: is short, a description of the properties of the current building stone

This exercise is described in Wetzel, L.R. 2002. Building stones as resources for student research. Journal of Geoscience Education. 50(4): 404-409.

Sites that include information (and photos) of building stones include:

• Building Stones of Maryland (more info) : Descriptions of some of the most common stones produced from Maryland quarries emphasizing their history and detailing some of the more famous places where they are used (some of which are outside the state).
• A Geologic Walking Tour of Building Stones of Downtown Baltimore, Maryland (more info) : The Maryland Geologic Survey offers a map, lots of photos and descriptions of twelve structures built from a variety of rocks.
• Building Stones of Our Nation's Capital (more info) : A USGS site detailing the stones common in Washington D.C., their descriptions and origins, how they've been affected by acid rain, maps for a walking tour, and the DC area's geologic history.
• The City Rocks: Exploring the Hidden World of Building Stone ( This site may be offline. ) : Very basic descriptions of stones used to build major public buildings around the U.S. Includes a nice bibliography.