Holywood Priory is a medieval monastic ruin located in Holywood, County Down. The site was originally established as a monastery by St. Laiseran in the early seventh century, though most of the surviving stone ruins belong to an Augustinian abbey constructed during the late twelfth or early thirteenth century. It was officially dissolved on New Year's Day in 1541 during the reign of King Henry VIII.
I was here geocaching and I spotted an unusual feature in one of the blocks on the front of the building. The photo below will help you locate it - looking at the doorway nearest the entrance, it's low on the right hand side.
1) Describe the line running across the block - run your hand over it.
- is it smooth?
- does it stand out against the block or is it set into it?
- what colour is it?
2) Can you identify the feature? - use the descriptions below to help you
3) Briefly and in your own words, explain how this feature was formed
4) Take a photo of yourself at GZ, or an identifying item, being careful not to reveal any of the answers to the questions.
If logging as a group, all members of the group must be in the photo - if you don't want to be in the photo, you need to upload your own unique photo showing a personal item or your caching name. The person sending answers must mention in their message the cachers they are sending answers for.
Please submit your answers via message though the Geocaching website or by sending me an email - there is no need to wait for a response before logging your find.
Distinguishing Stylolites and Veins
Stylolites and veins looks different in appearance and texture. Stylolites present as dark, jagged lines that track into the stone block, often feeling slightly recessed In contrast, veins appear as lighter bands - often white or cream - that stand out in relief because their mineral filling is more resistant to weathering than the surrounding sandstone.
Formation of Stylolites
Stylolites form through pressure solution, a process driven by tectonic compression or deep burial loading. Under high stress, localised areas of the sandstone dissolve, allowing soluble minerals like quartz to migrate away in fluid. Insoluble materials, like clay and dark minerals, are left behind to form the jagged dark line.
Formation of Veins
Veins develop when tectonic forces pull the sandstone apart, creating open fractures and cracks within the rock. Mineral-rich fluids then circulate through these spaces, gradually precipitating minerals like quartz or calcite out of solution. Over time, these mineral deposits crystallize and completely fill the void, creating a solid, distinct band.