The posted coordinates are a good place to park and start.
WEATHERING
Weathering is defined as the breakdown of rock, that is without being moved. Weathering processes depend upon the presence of water, the temperature, the mineral composition of the rock and its chemical composition.
WHY HERE?
Headstones are subjected to weathering simply by standing in a cemetery. Headstones provide a useful means of observing and measuring the weathering of different types of rock over relatively long and easily measurable periods of time. The markers in this cemetery contain all three types of rocks: Sedimentary (sandstone), Igneous (granite) and Metamorphic (marble) making it valuable for comparison of headstone weathering.
WEATHERING FACTORS
The weathering on headstones is a product of four interconnected factors.
The four factors are:
Material the headstone is made from
Environment the headstone is in
Form of the weathering on the headstone
Process by which the headstone is weathered
Weathering Form
|
Characteristics
|
Granular
disintegration |
Mineral grains are visible as protruding forms on the surface, which has a 'sugary' feel when touched. Little or no flaking. On some headstones the edges of the lettering will become rounded and less distinct as weathering proceeds. |
| Flaking |
Fragments of varying sizes become detached from surface. These fragments may be derived from the main body of a sheet of detaching material or to the underlying mass of stone. |
| Blistering |
A domed or raised surface to the headstone appears. This dome sounds hollow when tapped. Over time the dome bursts and flakes of stone fall away from the central dome. The inside of the blister may appear to be composed of more friable material. |
Contour
weathering |
A whole surface breaks away from the headstone as a single sheet. The sheet tends to follow the contours of the underlying carved form. |
| Pitting |
Distinct depressions on the surface of a headstone. These can be shallow or deep in form. Measurement is possible either directly by measuring length, breadth and depth or indirectly by classifying into classes based on size. |
| Black crusts |
Black deposits often found in sheltered areas. On marble headstones these crusts often have 'cauliflower' forms at the micro-scale. This is indicative of calcium sulfate, a crust formed by dry deposition. Where crusts form on exposed areas these are likely to be deposits of soot and particulate matter alone. |
| Organic forms |
Often there are algae growths or lichen on the headstone surface. These tend to indicate the presence of a regular supply of moisture to a surface. It is unclear whether these organic forms retard or enhance weathering. In extremely moist conditions on old headstones mosses can be found. |
LOGGING REQUIREMENTS
In order to log this EarthCache, send me your answers to the following questions either through email or messaging from my profile page.
Find each of the following headstones to make your observations.
Reference point 1: Harriet - N 42° 51.353' W 83° 27.377'
Describe at least two forms of weathering.
Reference point 2: Brown - N 42° 51.336' W 83° 27.318'
Describe at least one form of weathering.
Reference point 3: Gordon - N 42° 51.332' W 83° 27.353'
Describe at least one form of weathering. Pay attention to the back.
Reference point 4: Adams - N 42° 51.328' W 83° 27.345'
Fanny and Asahel - Describe at least two forms of weathering.
* Pictures are not required but are appreciated. Please post a pic of you or your GPS with anything you find interesting around the cemetery.
Resources
https://spadeandthegrave.com/2019/05/05/the-geologic-composition-weathering-of-gravestones/
https://www.ucl.ac.uk/earth-sciences/impact/public-engagement/londons-geology/londons-geology-fieldwork/st-pancras-gardens/gravestone#:~:text=In%20simple%20terms%2C%20weathering%20is,to%20300%20years%20or%20more).
https://www.wyorksgeologytrust.org/misc/Teaching%20weathering%20in%20West%20Yorkshire.pdf
https://www.livescience.com/18681-cemetery-gravestones-weathering-acid-rain.html