Here you will find some nice examples of Aplite Veins (dykes)! Although they have not been viscous for millions of years, they would have been at some stage, just before being fully formed. Dykes are always younger than the rocks that contain it, as they are made of new magma which has pushed its way through the cracks in the existing granite. This magma cools more quickly than the original surrounding granite did, not allowing the crystals time to form, so they are very small!
The whole area here is covered in large granite slabs, through which you will find numerous veins ranging in thickness passing through. These veins are made of aplite. When the hot magma was almost completely cooled, it flowed through the cracks in the rock, depositing their dissolved content as they cooled down.
Aplites are fine-grained, intrusive igneous rock composed mainly of grains of quartz and feldspar which can come in a range of colours including red, orange, pink and white etc. Aplites are found only in rock like the granites that you see here. The type of granite here is known as felsic rock. Which is rock that is relatively rich in elements that form feldspar and quartz.
To log this cache you will need to answer the following questions:
At the posted coordinates, you will find the start of a large vein heading 12m roughly in an easterly direction, it then splits into another main vein and continues easterly for another 12 or so metres before suddenly significantly changing direction.
1. What colour is the vein, and which mineral do you think it is predominantly composed of?
2. Approximately what angle is the change in direction of the vein?
3. Are the particles in the vein finer or courser than that of the surrounding slab, and why do you think this is so?
4. Take a photo of the vein (not at the change in direction), including your cacher name, or GPS or foot etc, and include it in your log.
Note - you may log your find for this Earthcache immediately but please send me the answers to the above questions within 1-2 weeks, or you log will be removed... Also note, dty73 assisted with setting this cache, and will log her visit once the FTF is taken.