Ireland is an island in northwest Europe in the north Atlantic Ocean. The island lies on the European continental shelf, part of the Eurasian Plate. The island's main geographical features include low central plains surrounded by a ring of coastal mountains

The oldest known Irish rock is about 1.7 billion years old and is found on Inishtrahull Island off the north coast of County Donegal and also at Annagh Head on the Mullet Peninsula. In other parts of Donegal, scientists have discovered rocks that began life as glacial deposits, demonstrating that at this early period, part of what was to become Ireland was in the grip of an ice age. However, because of the effects of later upheavals, it is almost impossible to sequence these early rock layers correctly.

About 600 million years ago, at the end of the Precambrian super-eon, the Irish landmass was divided in two, with one half on the western side of the Iapetus Ocean in Laurentia and the other on the eastern side in the micro-continent Avalonia, both at a latitude of around 80° South, close to what is now northwest Africa. From the evidence of fossils found at Bray Head in County Wicklow, Ireland was below sea level at this time.

Over the next 50 million years, these two parts drifted towards each other, eventually uniting about 440 million years ago. Fossils discovered near Clogherhead, County Louth, show the coming together of shoreline fauna from both sides of the original dividing ocean. The mountains of northwest Ireland were formed during the collision, as was the granite that is found in locations in Donegal and Wicklow. The Irish landmass was now above sea level and lying near the equator, and fossil traces of land-based life forms survive from this period. These include fossilised trees from Kiltorcan, County Kilkenny, widespread bony fish and freshwater mussel fossils and the footprints of a four-footed amphibian preserved in slate on Valentia Island, County Kerry. Old Red Sandstone also formed at this time.

Between 400 million and 300 million years ago, Northwest Europe – including Ireland – sank beneath a warm, calcium-rich sea. Great coral reefs formed in these waters, eventually creating the limestone that still makes up about 65 per cent of the rock mantle of the island. As the waters receded, tropical forests and swamps flourished. The resulting vegetable debris eventually formed coal, most of which was later eroded. This period, known as the Carboniferous period, ended with further tectonic movement which saw Ireland drift further northward. The resulting pressure created those Irish mountain and hill ranges that run in a northeast to southwest direction.

By 250 million years ago, Ireland was at the latitude of present-day Egypt and had a desert climate. It was at this time that most of the coal and sandstone were eroded. The thinner layers of limestone in the south of the country were also partially affected by this erosion. The limestone that was exposed by the disappearance of its sandstone mantle was affected by carbon dioxide and other factors resulting in a karstic landscape that can still be seen in the Burren in County Clare. Shortly after this period, organic debris in the seas around Ireland began to form the natural gas and petroleum deposits that now play a role in the economy of Ireland. Then, about 150 million years ago, Ireland was again submerged, this time in a chalky sea that resulted in the formation of chalk over large parts of the surface. Traces of this survive under the basalt lava that is found in parts of the north.

About 66 million years ago, the volcanic activity that formed this lava began. The Mourne Mountains and other mountains in the northern part of the island formed as a result of this activity. Climatic conditions at this time were warm and vegetation thrived. Vegetable debris in the Antrim Depression formed deposits of brown coal or lignite which remain untouched down to the present time. The warm conditions produced high rainfall that accelerated processes of erosion and the formation of karstic landscape forms.

By 25 million years ago, Ireland was close to assuming its present position. The long period of erosion had resulted in considerable soil formation and most of the rock mantle was covered. In areas with good drainage, the covering consisted of brown or grey soil, while in poorly drained areas, black clay tended to dominate. As the climate cooled, soil formation slowed down, and a flora and fauna that would millions of years later be familiar to the first human inhabitants, began to emerge. By about three million years ago, the present landscape of Ireland had more or less formed.

Since about 1.7 million years ago, the earth has been in the grip of a cycle of warm and cold stages and these have, inevitably, affected Ireland. The earliest evidence we have for this effect comes from the period known as the Ballylinian Warm Stage, some half a million years ago. At this time, most of what are now considered to be native Irish trees were already established on the island. The action of the ice during the cold stages was the major factor in bringing the Irish landscape to its current form.

Healy Pass lay within the Caha Mountain Range (An Ceachach in Irish) are a range of low sandstone mountains with the highest peak being Hungry Hill.

Found in southwest Ireland, Healy Pass is a perfect diversion from the longer Ring of Beara driving route. The serpentine R457 winds through a desolate, other worldly landscape, passing between two of the highest summits in the Caha mountain range. The landscape is littered with glacial rocks.

When you reach the highest vantage point of Healy Pass and stop to admire the view. Look around at the glacial rocks and especially when you look to the horizon, you will wonder awe just how far some of these rocks have travelled to there current resting place.

To Claim This Earthcache

Now walk the few metres to the coordinates, which you will find a small group of rocks. Within these rocks lay a few gemstones. Study these and then answer the following questions to claim this earthcache.

1) What is the closest colour of these stones. A= Red, B= Green, C= Yellow or D= White

2) Count the main groups you see. How many? A= 1 or 2, B= 3, C=4 or more?

3) What type of Gemstone do you think this group is? A= Diamonds, B= Quarts, C= Garnets, D= Fools Gold

Internet research now required.

4) Hungry Hill is the highest point on Caha Mountain Range. How high in metres is it?

5) Tectonic Plates are referred to as what _______ belt principle.

6) You may upload as many photos as you wish (optional) however, please do not show images of the mentioned gemstones or your log will be deleted immediately and you will then have to reclaim your find.

Send your answer like this example ; C, A, A, 524m, Leather  

DO NOT POST ANSWERS IN YOUR LOGS. THANK YOU.

You may automatically claim "after you have sent me your email with answers. ""NOT BEFORE"

Should your answers be incorrect, I will contact you and assist you to gain the correct ones.