Offa’s Dyke Path 5, Trevor Quarry, Eglwyseg EarthCache

This cache has been archived.

Geocaching HQ Admin: It has now been over 30 days since Geocaching HQ submitted the disabled log below and, unfortunately, the cache owner has not posted an Owner maintenance log and re-enabled this geocache. As a result, we are now archiving this cache page.

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Hidden : 9/9/2010
Difficulty:
1 out of 5
Terrain:
2 out of 5

Size: Size: other (other)

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Geocache Description:

This small quarry has alternating layers of limestone and mudstone. These rocks were the sea bed of a shallow tropical sea in the southern hemisphere about 350 million years ago. These rocks contain many fossils of the creatures that lived in those seas. The rocks here are part of a geological Site of Special Scientific Interest (SSSI) and it is illegal to use a hammer to remove fossils from the rocks.

This EarthCache is one of a series of caches along the Denbighshire section of the Offa’s Dyke Path. Together the Offa’s Dyke Path EarthCaches explore the rocks and landscape, which underpin, the heritage, culture and biodiversity of the area.

The rock of Trevor Quarry is limestone (Fig 2). It was laid down about 350-325 Ma during the Carboniferous Period. During this time, Wales lay on the edge of a huge continent south of the equator with a hot humid climate called Gondwana.

The rocks are laid down in layers or beds of alternating limestone and mudstone. The limestone represents normal conditions with animals living in calm waters. The mudstone represents changing, possibly stormy conditions that churned up the seabed. When the mud settled out it smothered the layers of brachiopods on the seabed, probably killing them.

Over the last 350 million years the rocks have been lifted up by mountain building events (plate tectonics) and are now tilted to the north east and about 275 m above sea level.

The many fossils, corals, crinoids, brachiopods and other marine animals fossilized in the rock of Trevor Quarry show that the seabed teemed with life. One fossil is as big as your fist. These are called Gigantoproductus giganteus. The clue to their size is in the name.

The fossilized animals found at Trevor Quarry were part of a reef system. Some of the fossils are in growth position (Figs 3 & 4) but some are overturned and were probably broken during a storm.

Fossils of the animals that are found here in Trevor Quarry were part of a reef system, illustrated below (Figs 6 & 7 to follow).

To log this Earthcache:

On the back (North east) wall of the quarry there are many layers of limestone and mudstone with corals and brachiopods

1. Find a layer with brachiopods (near the entrance)
What is the size of the largest brachiopod you can find?
2. Find a layer with coral
What is the size of the coral?
Is it a solitary or colonial coral
3. Post a picture of your coral or brachiopod with your GPS (optional)

It is illegal to take any fossils out of the cliff face. You may take any loose fossils you find on the floor of the quarry

Additional Hints (No hints available.)



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