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Max Schadt
Steve Roof
Earth Resources
31 September 2009
Tombstone Weathering Study
Dear Hampshire Alumna,
I am pleased by your request for us to research tombstone quality, as it shows you have
confidence in our geological knowledge. Fortunately, I believe we will be able to advise you
towards the most durable rock type in order for you to have a longstanding, legible, and beautiful
tombstone. Thank you again for contracting us; I hope you find our results to be helpful.
My partner and I started off our study with a discussion, in which we thought up
numerous hypotheses as to what trends we would discover. The predominant factor we
anticipated was obviously the hardness of the various rock types. Consequently, our hypothesis
was that the hardest rock type would weather the least and thus make the best tombstone. This
was our primary theory, although we also considered other factors such as the variability of the
original rock quality, the quality of the engraving, and the direction the tombstone is facing (if it
faces west it is exposed to most weather patterns, whereas if it faces east it is somewhat protected
from them). Unfortunately, these factors are more difficult to quantify and test, so we did not
attempt to record and calculate these aspects.
For our field study we headed off to the Amherst Cemetery to analyze tombstones that
have undergone the same weathering as where you would like your final resting place to reside.
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Since we already had a working knowledge of rock types and identification, it was simply a
matter of inspecting tombstone specimens and recording their rock type, age, and degree of
weathering. At least it sounds simple, but getting thorough and accurate ratings proved to be a
more exhausting task then we previously anticipated. Our methodology for ranking the
approximate level of weathering was to use a ten point scale, with one being completely illegible
and ten being perfectly intact.
We based our rating primarily on
the legibility of the lettering, and
we gave some consideration to
the overall quality of the
tombstone. At the beginning of
our field study, my partner and I
took three photographs by which
to compare the rest of our
samples. The picture on the right
is an example of a schist
tombstone. Due to its extreme
illegibility, it is our definition of
a 1 on the rating scale. Based on
the age of the surrounding tombstones, we estimated this piece to be about 220 years old. At
times it was challenging to rate each tombstone fairly, especially since each rock type exhibited
different weathering characteristics. For example, marble tombstones showed a tendency to
erode in a way that made them look like they were literally melting over time. This erosion left
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very small, sugar-like granules over
the surface of the tombstone, giving
it a frosted look. This particular
marble tombstone on the right is the
example my partner and I used to
define a 5 on our rating scale.
The first system we used to
choose our specimens was mostly
random; we walked around the
cemetery and documented whichever
tombstones caught our eyes. We did
have some organization to it though.
We made sure that we had between
five and ten examples of each rock type, and that each group type had a wide range of ages.
Unfortunately, when we compiled the data into graph form, it became evident that this wasn’t the
most effective method. The graph was very inconsistent and showed no general trend because
some rocks that were old had high ratings while some rocks that were newer had low ratings.
My partner and I discussed our methodology and we concluded that our results were
questionable due to the randomness of our documentation. If we had used the same method but
had included every single tombstone in the whole cemetery, then it would have been accurate.
But because our sample size was too small, there was not a large enough representation of
different tombstone ages and ratings. To make up for this error, we went back to the Amherst
Cemetery to collect all new data. This time, we decided to split our samples up into age
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groupings of fifty year intervals, while also recording the exact age of each tombstone. For
example, if a tombstone was from 1805, it would go in the 1775-1825 group. This new system
allowed us to calculate the average rating for each rock type in each age group. We went
meticulously through the entire cemetery to gather all of the data. We examined five tombstones
of each rock type for each fifty year group. Additionally, by using this system, we were easily
able to observe the time periods in which each rock type was a popular tombstone material. For
example, we didn’t find any granite tombstones older than 159 years, and we didn’t find any
schist tombstones newer than 199 years old. We also didn’t find any slate newer than 1831, any
sandstones newer than 1902, or any marble newer than 1956. This may somewhat be due to the
relatively small amount of new graves the cemetery has, but I think it also clearly defines the
time periods each rock type was used.
The next step in our study was to examine the data. My method of calculation was to
average the rating and age of each rock type based on which fifty year age interval they were in,
which this graph represents:
Tombstone Weathering Patterns
Average Rating
12
10
8
Schist
6
Slate
4
Sandstone
2
Marble
0
0
50
100
150
200
250
Average Age Based on Grouping
Granite
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As you can see, the data we gathered gives an accurate representation of how each rock type
weathers through time. However, as I mentioned above, there are no results for some rock types
at certain time periods because there were no tombstones from that era. In order to identify how
each rock type would measure from present day all the way back to 1775, I calculated the
approximate weathering rate of each rock type based on the trends that can be drawn from the
above graph.
Average Ranking Per Section
Predicted Weathering
12
10
8
6
Slate
4
Granite
2
Sandstone
0
Schist
Marble
Age in 50 year sections
These predictions are based on the average rating for each rock type from the 1775-1825 time
period (except for granite, which is based on the 1825-1875 group since there are no samples
from 1775-1825). My first assumption for these calculations was that if a brand new tombstone
of any rock type was erected today, it would rate as a 10 on the weathering scale, and would
continue to be a 10 for about the next fifty years. My other assumption was that the rate of
deterioration of the tombstone would be consistent throughout time. Here is an example of my
calculations for schist: I started with the oldest average rating, which is 2.8. I subtracted 10 (the
highest possible rating) by 2.8 to get 7.2, and then I divided 7.2 by 4 (the number of time
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intervals between the newest and oldest groups). The quotient is 1.8. This number represents
how much schist’s average scale ranking lessens per each fifty year period. If it was a 10 from
present day to 1975, it would be an 8.2 from 1975-1925, a 6.4 from 1925-1875, a 4.6 from 18751825, and finally a 2.8 from 1825-1775. I used the same method for all of the other rock types.
My partner and I did our very best to discover what type of rock the optimal tombstone is
made out off, and even though I’m confident with our conclusions, I would like to mention some
other factors that could come into play. While completing this study, we had to make some
assumptions we couldn’t definitively prove, and ignore other factors that we couldn’t easily
calculate, such as: the original quality of all the rocks were the same, the original quality of all
the engravings were the same, there were no differences in chemical compositions among the
same type of rock, weather affects different types of rocks in the same way, and whether the
tombstone was standing vertically or laying on the ground horizontally. The most substantial
and important factor (and probably the most inconsistent) of all is the objectiveness and
accurateness of my partner and my rankings. Concurrently, if we were to do this study again, I
know I can at least speak for myself in saying that I would change a few things in order to get rid
of some of the unresolved factors. I would take the time to document every tombstone in the
cemetery, as this is the most conclusive method. Also, I would observe weathering effects on
both sides of the tombstone, in order to conclude if direction could be a significant factor.
Lastly, I would design a new, objective rating technique that would take into consideration the
appearance of the entire tombstone.
Although our first system of data collection and analysis wasn’t highly successful, I feel
that our final methodology and results are much more conclusive. Unless we had done a
complete analysis of every tombstone in the entire cemetery, I can’t think of a better way we
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could have designed this study that would still give a result that shows a very clear pattern of
deterioration due to weathering. According to the graphs, marble and schist are the worst at
standing up to the weather, as they both have a rating of 2.8 at their lowest. Sandstone is next at
4.4. Granite’s weathering resistance is difficult to compare to the others because there were not
any granite tombstones older than about 160 years. However, based on my projections, a granite
tombstone would have a rating of approximately 4.7 from 1775-1825. Lastly, slate’s lowest
average rating is 7.2. Therefore, it seems slate comes out on top. However, take into
consideration that this rating scale is based primarily on the writing and engraving of the
tombstone, not the overall appearance. Nevertheless, the slate tombstones’ general coloration
and form did look much better than schist, marble, and sandstone tombstones of the same period.
But, which rock type makes the most weather resistant tombstone remains unclear to me until I
can directly compare similarly aged granite and slate tombstones. In spite of this, taking into
account the very detailed engravings that slate tombstones can have because of how fine the
stone is, it is my recommendation that you invest in a slate tombstone to signify and honor your
memory after you depart from this life. It is what I would do for myself. Besides, I would only
recommend the absolute best for a Hampshire alumna.
Sincerely,
Max Schadt