Pullar Memorial Park is a small park on the edge of the charming little town of Bridge of Allan just north of Stirling.
When visiting the park, I noticed some interesting features on the pillars between the road and the war memorial.
"Xenolith" literally means "foreign rock" and gives an insight into the formation of igneous rocks a long time ago.
Have a look at the pillars - with the war memorial at your back, you want to be looking at the left pillar.
1) Describe the largest xenolith you can see in the pillar - what shape is it, what size is it, what colour is it?
2) Describe how it looks different to the surrounding rock - what colour is the rest of the pillar, what size crystals are present?
3) Why do you think the xenolith is there? Use the infomation below to help with your answer.
4) Take a photo of yourself at GZ, or an identifying item, being careful not to reveal any of the answers to the questions.
Please submit your answers via message though the Geocaching website - there is no need to wait for a response before logging your find.
Xenoliths
Xenoliths, are foreign rock inclusions found within igneous rock formations, such as granite. Their formation begins deep within the Earth's crust, where molten magma slowly cools and solidifies to form granite. During this process, pockets of magma may intrude into existing rock formations, incorporating fragments of the surrounding rock into the cooling magma. These fragments, known as xenoliths, are often of different composition and texture compared to the surrounding granite. As the magma cools and crystallizes time, the xenoliths become trapped within the granite, preserving a snapshot of the geological history of the area. Studying xenoliths provides valuable insights into the complex processes occurring beneath the Earth's surface and aids in understanding the evolution of Earth's crust.
Xenoliths are usually visible. They have a different color and density than the surrounding igneous rock. Xenoliths can be as small as a grain of sand or as large as a football, and as long as several meters.