The upright slabs that you see as you walk along the Cliffs of Moher were added in the 1830s, as a protective barrier but also to provide work for the locals. These may obstruct the view, but this is for the safety of visitors, and somehow also the topic of this Earthcache!

Logging Tasks

Send the answers to the following:

1. Attach a photo to your log. Choose a Moher flagstone that contains fossils with a thumbs up as proof of your visit. Remember: the stone with long squiggly lines are of interest. If it's somewhat straight, that is the slab of interest for GCATAXD
2. The long winding marks are fossils. Of the 6 ways mentioned in the listing, which form of fossil is this?
3. Obviously no animal can be that thick and long. With that in mind, what type of fossil from the 4 mentioned below do the Moher Flagstone contains?

Fossils

Moher flagstone bearing fossils

One very interesting feature found in sedimentary rocks are the presence of fossils. A fossil is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved in amber, hair, petrified wood, oil, coal, and DNA remnants.

There are 6 ways that fossils can be formed:

• Unaltered preservation (like insects or plant parts trapped in amber, a hardened form of tree sap)
• Permineralization (in which rock-like minerals seep in slowly and replace the original organic tissues with silica, calcite or pyrite, forming a rock-like fossil - can preserve hard and soft parts - most bone and wood fossils are permineralized)
• Replacement (An organism's hard parts dissolve and are replaced by other minerals, like calcite, silica, pyrite, or iron)
• Carbonization (in which only the carbon remains in the specimen - other elements, like hydrogen, oxygen, and nitrogen are removed)
• Recrystalization (hard parts either revert to more stable minerals or small crystals turn into larger crystals)
• Authigenic preservation (a process which leaves a negative impression, or indent, of an organism in rock after the organism itself has deteriorated).

There are 4 types of fossils:

• Mold fossils (a fossilized impression made in the substrate - a negative image of the organism)
• Cast fossils (formed when a mold is filled in)
• Trace fossils/Ichnofossils (fossilized nests, gastroliths, burrows, footprints. Anything not of the organism, but proof that it exists!)
• True form fossils (fossils of the actual animal or animal part).

Local Info

The upright slabs you see are Moher Flagstone - thin-bedded sandstones that are often covered in horizontal, long sinuous marks about 1-2cm wide. They often have a central ridge or furrow. Sometimes you will see thin, internal curved bands; these are the layers of sediment that the creature pushed backwards behind itself in the burrow. This is what filled the burrow and stopped it from collapsing afterwards. The creature that burrowed through the sand is thought to have been a mollusc of some kind.