Visiting recently, I walked past this impressive war memorial and had a look. Erected in 1927, the Diamond War Memorial is located on The Diamond in the centre of Derry, County Londonderry, Northern Ireland. It is dedicated to the citizens of the city who lost their lives while in military service during World War I.
Depending on how busy it is, you may be able to park close by.
1) Describe the stone that makes up the pillar. What does it look like, what colour is it, what size are the grains and particles that make up the stone.
2) Based on the descriptions of the different types of stones below, which do you think has been used to make this pillar for the memorial?
3) Can you spot any fossils? Use the information below to identify any you find.
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 or by sending me an email - there is no need to wait for a response before logging your find.
Types of Portland Stone
Roach
The uppermost layer of the Portland Freestone Member is called Portland Roach and is rich in shell fossils. Acidic groundwater has dissolved many of the shells, leaving empty spaces where the shells once were.
Whitbed
The fossil content in Portland Whitbed varies, ranging from being rich in shells to almost free of them.
Basebed
Basebed has a clean, uniform texture with minimal shell content, making it ideal for carving fine details. Though slightly less durable than Whitbed in exposed locations, it is excellent for monumental and carving work on prestigious buildings.
Fossils
Portland limestone is full of marine fossils because it formed in a shallow sea. Some common fossils include:
-
Bivalves: Two-shelled marine organisms like clams and oysters. Their shells or imprints are often well-preserved in the limestone.
-
Gastropods: Snail-like creatures that left behind coiled shells, providing insights into the Jurassic marine environment.
-
Ammonites: Extinct marine mollusks with spiral shells, used as index fossils to date rock layers.
-
Brachiopods: Marine animals with hard shells on their upper and lower surfaces. They are less common but still found in Portland limestone.
-
Echinoids: Sea urchins and similar creatures, often leaving behind spiny fossils.
-
Corals: Fossilized corals, indicating ancient reef environments, though they are less common in Portland limestone.