The coordinates will take you to 21- 23 Market Place in the town of Barnard Castle. The lower part of the building is made from granite.
The purpose of this earthcache will help you learn about Xenoliths and how they are formed.
Igneous rocks form when molten rock originating from deep within the earth’s crust cools (either below the surface as an intrusion e.g. granite, or above the surface as an extrusion e.g. basalt lava). The resulting igneous rock is composed of interlocking crystals, the size of which depends on the time taken for the molten rock to cool. If the molten rock cooled rapidly, the crystals are small if it cooled slowly, the crystals will be large. A common building stone of the latter type is granite – due to the large crystal size in granite it is a very aesthetically pleasing rock, and as such is found in many forms, cladding buildings around Glasgow and also being used for ornamental pillars and balustrades.
A xenolith is an inclusion in the magma which formed the granite and quite often it is part of the existing country rock into which the magma was forced.
Look at the granite window sill.
There is a large xenolith here. To claim this Earthcache please answer the following questions:
1. You should be able to see a large xenolith . What distinguishes it from the granite surrounding it?
2. Describe the shape and size of the xenolith.
3. How do you think the xenoliths got there?
4. Please provide a photo of yourself or a personal item near GZ (without giving away the answers).
Answers to questions 1-3 should be sent by the message centre or email. Please DO NOT include the answers in your log.
Please send your answers BEFORE logging the cache. You do not need to wait for a reply, but if there is a problem, we will let you know.
ANY LOGS ENTERED WITHOUT ANSWERS BEING SENT WILL BE DELETED.