A merestone is a stone which indicates a boundary.
The Southam merestone was first mentioned in a charter written in Old English. The original dates from 998, during the reign of Aethelred the Unready. Unfortunately, as often happens, it was lost. The current stone was erected to mark the milennium. More interesting information about the Southam merestone can be found at https://www.southamheritage.org/2017/11/14/the-merestone/
Now for the lesson!
You might know that there are three main types of rock: Sedimentary, Igneous and Metamorphic.
Sedimentary rocks are formed from bits of plant and animal remains, and older rocks, laid down often by water. They can contain fossils, and you can age a sedimentary rock by the fossils contained within it. They don't often contain crystals, but do generally contain several different layers, and you can sometimes see larger pebbles or rocks of other types of stone within them. Most sedimentary rocks are porous, but not all of them are. They tend to err on the more crumbly side, and although some can be incredibly hard, many are more susceptible to weather and wearing away than the igneous and metamorphic rocks.
Igneous rocks are formed by magma and/or lava cooling under various conditions. They are thus very hard, and resistant to high temperatures. You can tell how the lava cooled by examining the rock - pumice, for example, is formed when lava erupts with gas in it, so forming bubbles, which then get frozen as it cools resulting in a stone full of holes, whereas obsidian is formed by lava falling onto a cool surface and solidifying quickly, leaving a glassy effect. Different minerals within the rock can result in different colours. One key feature of igneous rock is the lack of fossils, as the high heat and quick cooling mean fossils cannot exist. Generally, the quicker the igneous rock cooled, the smaller the crystals you will find within it.
Metamorphic rocks are formed when either igneous or sedimentary rocks are subjected to high heat and/or pressure. They often contain crystals, and they can look squashed, with distinct layers called foliation. Slate is an example of this, where the layers can easily be separated, although not all metamorphic rocks can be split so easily. Another common feature of metamorphic rocks is lineation, which is the intersection of two foliations and can sometimes be seen as a line running perpendicular to the layers.
In order to log this cache as found, you need to answer the following questions and send the answers to the cache owner, either via email or through the Message Centre:
Question 1: Using the information above, which of the three main types of rock do you believe the merestone to be? Which features of the stone tell you this?
Question 2: There is one of the three types of stone which would be more unsuitable for a long-lasting boundary stone. Which do you think this is, and why?
Question 3: Compare and contrast the features of the merestone with the features of the stone that makes up the plaque. What similarities and differences can you see?
Please do not post any spoilers in your logs!