Calthemites
Calthemites are secondary deposits, i.e it forms from chemical alterations or weathering from a primary rock. In the case of this medieval building, the primary rock here is limestone, although examples of calthemites can be formed from concrete too. Their formation and shape are like speleothems, in particular stalactites, but due to the strict definition of the word calthemites cannot be called speleothems.
Limestone is a sedimentary rock that is dominantly composed of the calcium-bearing carbonate minerals calcite and dolomite. Calcite is chemically calcium carbonate. This rock undergoes weathering and chemical alteration, allowing calthemites to form as mainly white calcium carbonate. Impurities such as iron oxide (rust) can sometimes give the calthemites a red or orange tinge.
When water (leachate) rich in CaCO3 evaporates, it leaves behind the calcium carbonate. The growth rate of the calthemite depends on some factors, but the most interesting feature here is the diameter of the rods - the slower the drip rate, the thicker the diameter.
QUESTIONS
Tried my best to keep this EC listing as short as possible - no point having you read a wall of text for a quick smiley in the heart of Galway! Blake's Castle is the second medieval tower house in Galway City, so be sure to snag some photos while you're at it.
For this, you're going to have to look high up on the castle.
- Facing the castle, which side can you see the calthemites on? Can you make an inference as to why this is the case?
- Note the colours of the calthemites. What colours are there and what can you deduce from it?
- Look at the diameter of the rods. Can you tell if these are fast or slow drip rate speleothems?
- How do you see these calthemites change over time?
- Take a photo of something personal or something interesting that you have or bought in Galway (food counts too) and take a photo of it with the blue plaque on the castle. Attach this to your log.
I do not expect PhD level answers, nor do I overly care about wrong answers. As long as you have a good log about your experience and a photo, and you try to answer the questions as best as possible it is fine.