Questions - please send answers via the message centre or email within a reasonable amount of time.
- What are olivellites?
- What type of fossil are olivellites (trace or body)? Explain your reasoning.
- Describe the fossils in the stone below. What do they look like and how frequently do they appear within the stone?
- Post a photo into your log of yourself, your name on a piece of paper, or a personal item at GZ.
Liscannor Flagstone [1]
The posted coordinates bring you to a public footpath made of Liscannor Flagstone. Liscannor Flagstone is a type of sandstone from Liscannor, County Clare. It is formed from sediment deposited around 320 million years ago in an offshore river delta. Preserved within the stone are numerous fossils, including feeding trails from an unknown organism. Due to its durability, Liscannor Flagstone is commonly used across Ireland in paving, building, and in fireplace hearths.
Olivellites [2] [3]
As mentioned above, Liscannor Flagstone has preserved the feeding trails of ancient organisms. These fossilised trails are called Olivellites and can be seen meandering across the stone. After the sediment which formed the Liscannor Flagstone had been deposited, organisms burrowed through it in search of food. These burrows have been preserved and form the olivellites within the stone. While the burrows have been preserved, there is no sign of the organism which created them. As such, we don't know exactly what organism created them, but it is believed to have been ancient snails, worms, or crustaceans.
Types of Fossils [4]
Fossils can form in several different ways. Sometimes minerals fill small cavities in an organism or replace the organic matter altogether. Other times, the imprints of soft bodied organisms are impressed into sediment. Rarely, an organism may be preserved when it becomes trapped within amber.
Generally speaking, fossils can be split into two categories. Body fossils are the physical remains of an ancient organism. Hard parts of an organism (such as bones or shells) are more likely to be preserved than soft tissues. Trace fossils, also known as ichnofossils, are the fossilised evidence of an organism interacting with the environment (such as footprints or burrows). Importantly, trace fossils do not contain the organism themselves.
References:
1. https://www.ucc.ie/en/bees/outreach/geogarden/rock9/
2. https://www.researchgate.net/publication/264383642_Geology_of_Ireland_county_by_county
3. https://www.ucc.ie/en/fossil-heritage/irishfossils/olivellites/
4. https://www.nps.gov/subjects/fossils/about-fossils.htm