In this level of the project there are two ways to take measurements. The first can only be done on marble gravestones that have lead lettering (Steps 4a and 5a). The second way can be done on almost all marble headstones (Steps 4b and 5b). Read carefully all the notes for what you need to do for each type of marble gravestone. Remember that which ever method you use you you will need to log the data (Step 6).
If you are in a graveyard that has marble-lead gravestones then selecting which five marble-lead gravestones to collect the data for a graveyard may be a challenge, especially if you are in a large graveyard with many hundreds to pick from. Remember that we are trying to get a good representation of the gravestones and so we need to consider four things.
Different ages
The first thing is to select gravestones that are of different ages. Most gravestones are erected about one year after the person died and was buried. You will find that often more than one person was buried in the same grave, so look for the youngest date of death. So if two people were buried in the same grave and the stone has two death dates of 1879 and 1911, then its the 1911 date you will record. This is because the stone was most probably re-carved with the new date, new lead placed into the letters and re-polished flat, essentially resetting the weathering clock for the gravestone. Ideally it is best to use gravestones with only one name and date i.e. a single grave.
You should try and get two that are some of the oldest gravestones you can find. You should then find one gravestone that is one of the youngest you can find. And finally find two gravestones that are somewhere in between the oldest and the youngest.
Having these five gravestones spread in ages can provide some other important information like changes to the rate of weathering over time.
Upright (vertical) gravestones
The second thing is to only select gravestones that are completely vertical. Some gravestones are installed at an angle, or have moved so they are at an angle. To get data that we can compare, we need measurements from only vertical gravestones.
Facing direction
The third thing is to pick gravestones that face in different directions. This is because the orientation of the gravestone to the dominant rain direction and the drying effects of the sun can also affect the weathering of the marble, so you should try and get measurements from gravestones that face in different directions.
Some graveyards have all their stones facing in the same direction. But many have them facing in directions related to the changes of slope in the ground.
What ever is the case, you will need to work out the direction (in this case a compass bearing from 0 to 359 degrees) and record this for each stone. To get this direction, set your GPS into compass mode. Place the GPS against the face of the gravestone that has the lettering and then move the GPS away from the gravestone at 90 degrees to the face. The GPS will show you the direction the stone is facing. You may have to walk quite a few meters (feet) before you get a reading. Alternatively, you could use a magnetic compass that has bearings (1-360 degrees).
No restoration
The fourth thing to take into consideration is to make sure that the gravestone has not been restored. Sometimes families pay to have gravestones taken away and have new lead lettering and re-polished then replaced on site. These may be hard to recognize, but expect that they will appear to be in a much better condition than other gravestones of the same age. If you are in doubt, then pick a different gravestone.
No lichens or mold
The final thing is that the gravestone has to be relatively clean and free of mold or lichens. These ‘plants’ can get under the lead and lift it out giving bad data. Mold/lichens may only affect one part of the gravestone lettering, and so measurements could be taken from those letters away from mold/lichens. Alternatively, choose another gravestone if you can.
Measuring the distance from the front of the lead lettering to the marble needs to be done carefully with a micrometer. Rather than just taking one measurement per gravestone, we will take five measurements. This helps to average out any problems due to lead moving for other reasons.
To take a measurement, place the base of the micrometer against the lead so that the spine of the micrometer when pushed out will reach the marble. Make sure that the base is flat on the lead and not at an angle. Slowly push the spine out so it touches the marble then take the reading. For more help, see the section on "How to read a micrometer".
For this project we need measurements taken with two decimal places i.e. X.XX or XX.XX or XXX.XX.
For almost all cases, the reading should be less than a few millimeters. Record the information on the Gravestones Project Datasheet.
Move the micrometer to another lead letter on a different part of the gravestone and repeat. Do this three more times so you end up with five readings for the one gravestone.
Remember to show respect to the grave while you are doing your measurements. Stand to the side of the gravestone rather than directly on top of the grave. If you can’t take a measurement from the side, then find another gravestone.
To help us tie the two methods of measurement together, we would like you to measure the oldest gravestone you did using this method also using the method below.
If you are in a graveyard that has marble gravestones without lead lettering, then selecting which five marble gravestones to collect the data for a graveyard may also be a challenge. We are going to assume that when most gravestones are made that the front and back of the gravestone are parallel to each other. Sometimes, although rarely, gravestones are made where the front of the stone is at an angle to the back. We can't use these stones for this study.
Remember that we are trying to get a good representation of the gravestones and so we need to consider four things.
Different ages
The first thing is to select gravestones that are of different ages. Most gravestones are erected about one year after the person died and was buried. You will find that often more than one person was buried in the same grave, so look for the youngest date of death. So if two people were buried in the same grave and the stone has two death dates of 1879 and 1911, then its the 1911 date you will record. This is because the stone was most probably re-carved with the new date and re-polished flat, essentially resetting the weathering clock for the gravestone. Ideally it is best to use gravestones with only one name and date on them i.e. single graves.
We also notice that in some graveyards there are marble gravestones without a death date recorded on them at all. You will not be able to use these gravestones in this project.
You should try and get two that are some of the oldest gravestones you can find. You should then find one gravestone that is one of the youngest you can find. And finally find two gravestones that are somewhere in between the oldest and the youngest.
Having these five gravestones spread in ages can provide some other important information like changes to the rate of weathering over time.
Upright (vertical) gravestones
The second thing is to only select gravestones that are completely vertical. Some gravestones are installed at an angle, or have moved so they are at an angle. To get data that we can compare, we need measurements from only vertical gravestones.
Facing direction
The second thing is to pick gravestones that face in different directions. This is because the orientation of the gravestone to the dominant rain direction and the drying effects of the sun can also affect the weathering of the marble, so you should try and get measurements from gravestones that face in different directions.
Some graveyards have all their stones facing in the same direction. But many have them facing in directions related to the changes of slope in the ground.
Whatever is the case, you will need to work out the direction (in this case a compass bearing from 0 to 359 degrees) and record this for each stone. To get this direction, set your GPS into compass mode. Place the GPS against the face of the gravestone that has the lettering and then move the GPS away from the gravestone at 90 degrees to the face. The GPS will show you the direction the stones is facing. You may have to walk quite a few meters (feet) before you get a reading. Alternatively, you could use a magnetic compass that has bearings (1-360 degrees).
No restoration
The final thing to take into consideration is to make sure that the gravestone has not been restored. Sometimes families pay to have gravestones taken away and be re-polished then replaced on site. These may be hard to recognize, but expect that they will appear to be in much better condition than other gravestones of the same age. If you are in doubt, then pick a different gravestone.
To measure the weathering on these marble gravestones we are going to take five measurements using the micrometer calipers. We are going to take two measurements at the base of the stone. These need to be 20 mm (7/8 inch) from ground level, one on either side of the gravestone. You should record your thickness measurements 35 to 40 mm (1.4 inch) in from the side of the stone (this is about as far as a standard set of calipers can reach). We are also going to take two measurements on the side of the stone at 500 mm (20 inches) from ground level on either side. These also need to be measured 35 mm to 40 mm in from the side of the stone. If the gravestone is not tall enough to take the measurement at 500 mm above ground level, or if it is not possible to get all of these measurements because of the way the stone is placed, or if it is broken, you will have to select another gravestone. The fifth measurement needs to be taken in the middle of the stop along its top edge, no matter what the height above ground.
The measurements need to be taken and recorded in order, as shown on the image below and recorded on the datasheet.
The five sites to measure thickness on a gravestone. You need to always take and record the readings at the same locations on the gravestone each time.
To take a measurement, open the caliper ends of the micrometer wider than the thickness of the stone. Place them around the stone and then slide them in so that they touch the front and back of the stone. While the calipers are still touching the stone, read the scale on the micrometer and record the data. For more help, see the section on "How to read a micrometer".
Record the information on the Gravestones Project Datasheet along with the date on the stone, the family name etc.
Your Datasheet should look something like this (click for full size PDF):
Remember to show respect to the grave while you are doing your measurements. Stand to the side of the gravestone rather than directly on top of the grave. If you can’t take a measurement from the side, then find another gravestone.
Log onto EarthTrek and then select the Gravestone Project. Click on the Log Data button and complete the online form using the data you collected on the Graveyard data sheet. You will need to complete both the graveyard data and the gravestone data.
If you have measured gravestones using the thickness method, make sure you recorded the data online in EXACTLY the same fields as on the data sheet.