The First Steps EarthCache

The First Steps

This Earthcache will bring you to the Valentia Tetrapod Trackway in the northern part of the island Valentia. It shows one of the first real steps in the evolution from fish to mammals carved in the stones.

The Geology of Valentia Island

Several million years ago Ireland did not exist as we now know it. Ireland was not even in this place, but south of the Equator bordering a warm tropical sea. Since then, movement of the Earths crust has brought it to the present position. The province Munster was at this time a part of a huge coastal plain with mountains in the northern part. Great rivers cutting through these mountains carried enormous amounts of sand and silt to the ocean. All the rocks you see near the Trackway originated from these sediments.
When the rivers flooded, sheets of silt were laid down on the coastal plains. Ripple marks (see rock samples on the wall display) formed in shallow pools which later dried out but were again covered with new deposits of silt from further flooding. Over time, the silt was subjected to huge pressure and turned to stone. Today, erosion has once more exposed these ripple marks which were created 300 - 400 million years ago.

The Valentia Tetrapod Trackway

The impressions on the rocks at the given coordinates are petrified footprints of one of the first animals which walked on dry land. This animal, lizard-like in appearance, was one metre long and did not only leave footprints. You can see here and there the faint tracks of a "tail-drag". These would have formed when the animal dragged itself out of the water and walked on the wet mud. The prints would have rapidly filled with mud which turned to rock.

This track is one of the oldest in the world of a vertebrate (an animal with a backbone) walking on land. Before this, all known vertebrates were fish. Some of these had begun to live in the shallow water at the edges of rivers.

Gradually fins evolved into primitive legs. In addition these animals developed the ability to breath air out of water. They were the first tetrapods (four-footed animals). Over time they became more complex and evolved into mammals and (eventually) humans.

Valentia Island

Valentia Island is one of the westernmost inhabited locations in Europe with a permanent population of 650 peoples. The island is approximately 11 kilometres long and almost 3 kilometres wide. It can be reached by ferry, which sails from Reenard Point to Knightstown (from April 1st to September 30th), or by the Maurice ONeill Memorial Bridge at Portmagee. 

At Valentia Island you can see some other interesting places. The Island was the eastern terminal of the first commercially viable transatlantic telegraph cable. This cable was laid between Valentia Island to Hearts Content, Newfoundland in the year 1866. Some other additional cables followed making the County Kerry a major focal point for global communications until the carrier terminated its cable operations in 1966. Today you can see a very interesting memorial stone with samples of some submarine cables at the street on the way to the Tetrapod Trackway if you arrive from the bridge.

Nearby the Tetrapod Trackway you can visit the (archived) cache Mogh Roith (GCY4DB) with a nice grotto and a great view over Valentia Island.

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