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In this field exercise, you will determine the susceptibility of different rocks to weathering and perhaps even estimate some weathering rates. This cemetery exercise is also a good opportunity to identify the processes of rock weathering. Cemeteries are ideal places to study rock weathering because, in most cases, the dates on the stones give a good idea of the amount of time the rock slabs have been exposed to the elements. If you should happen to see a cemetery caretaker, be sure to ask how the headstones and monuments are maintained and cleaned. This will help you assess any human causes of accelerated weathering.
- Working knowledge of chemical and physical weathering processes
- Susceptibility of different rock types to weathering
- Practice recognizing rock types
- Calculation of approximate weathering rates
Context for Use
This is an excellent lab to use in an urban area where there are few natural outcrops. It is also a good lab to assign for homework if the lab periods are short (or nonexistent) and the cemetery is easily accessible by car, foot or public transportation.
Students should have some experience recognizing sedimentary, igneous and metamorphic rocks and also be able to distinguish felsic and mafic igneous rocks and volcanic and plutonic igneous rocks. The lab could either precede or follow a classroom lecture and discussion on weathering. In the latter case, students could be asked to summarize some specific observations and then these could be used to develop a list of weathering types. As with outcrops, tombstones weather by a combination of chemical and physical weathering processes that are easier to separate out in the abstract than in the concrete, so to speak. Nevertheless students generally have little trouble distinguishing the relatively slow weathering of granites from the more rapid weathering of marble and sandstone when comparing inscriptions and dates.
Cemeteries are wonderful ways to tie geology into human history. Commonly the tombstones are in languages of immigrant groups (in the Northfield, MN area, these include Norwegians and Czechs; one feature of the Bolton St. Cemetery in Wellington, NZ was the section with tombstones in Hebrew). There may be explicit stories (one of the earliest tombstones at Bolton St. is from a shark attack victim in Wellington Harbor) or implicit stories (the several children from one family who died within a few weeks of each other) on the gravestones.
This lab handout (Acrobat (PDF) 88kB Mar10 04)
for a cemetery in Wellington, New Zealand can be adapted for your area.
Teaching Notes and Tips
Depending on the size of the cemetery, this lab may take from one to three hours. In addition to systematic notes on tombstone material type, date, and indications of weathering, encourage students to take notes on the "stories" told by the cemetery.
If you require a written report from the students, it will be fairly easy to determine which ones really engaged with this assignment and which ones did not. The former will produce more detailed information about weathering and rock types and will have looked at more of the cemetery. The other students may produce a more cursory report that shows they have only looked at a few areas of the cemetery.
References and Resources
A related in-class exercise involves estimating tombstone weathering rates
Resource TypeActivities:Field Activity:
Field-Based Teaching and Learning
Grade LevelCollege Lower (13-14):
Ready for UseReady to Use:Meets Peer Review Standard:
Anonymous Peer Review, Ready to Use
Earth System TopicsSolid Earth:Earth Materials:
Human Dimensions/Resources, Earth surface
ThemeTeach the Earth:Teaching Environments:
Intro Geoscience, Teach the Earth:Course Topics:
Sedimentary Geology, Teach the Earth:Enhancing your Teaching:
Teaching in the Field