Welcome to Ross of Mull Granite EarthCache
Hidden : 6/20/2016
Difficulty:
3 out of 5
Terrain:
1 out of 5

Size: Size: other (other)

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Geocache Description:


As there is no plastic pot to look for, you need to visit the area and answer the questions posed on this page. You will also need to do a little bit of research. To be able to log a find, please send your answers to the questions. Thank you.
 Failure to submit answers (it is an earthcache logging requirement) will result in logs being deleted without notice .
Not a logging requirement but photos of you, or your caching group, would be appreciated......


You will have to park the car and walk towards the ferry to arrive at the published coordinates. Along the left hand side you will see small outcrops of granite. All around you is granite. Look at the large rock there.

1) Describe the appearance of the rock: the texture, the height and the coloration.
2) Which minerals do you think are responsible for the colours you see in the rock?
3) To show you have visited the location please look on the back of the nearby sign post and let us know the three dates shown on the label.

If you cross the roadway and glance to the beach you will see a large split granite boulder nestled on the sand.

4) This rock is not native to the area and was moved to its resting place a long while ago.... what is it called and how did it get there?


This is a part of Scotland in which the underlying geology truly dominates the landscape. Steep cliffs of lava, like those of Staffa, dominate northern Mull, while the high mountains of the south expose the roots of a huge volcano that erupted 60 million years ago. In marked contrast are the low-lying rounded knolls of pink granite and the welcoming sandy beaches of the Ross of Mull. Just a short distance from where you are standing are some of the oldest rocks in Scotland (about 2000 million yrs old), Gneiss, forming the low, craggy hills of Iona. The mountains show the effects of glaciers that covered the area during the Ice Age and all around the coast are signs of changing sea levels that followed the melting of the ice in recent geological time. The boulder on the beach was moved there by glacial action.

Mull is constructed rather like a multi-tiered wedding cake. Thick layers of basalt lava sit on top of a complicated basement of much older rocks which peep out around the edges of Mull rather like the silver base does on the lowest wedding cake tier.

Geologists love Mull because it has such a long and interesting history, with unique rocks and intrusions found nowhere else in the world.

Most of Mull is made of lava poured out of fissure volcanos when the North Atlantic was forming and Mull was torn apart from its ‘neighbour’ Greenland as the vast super-continent which once joined North America and Europe divided. The molten lava which erupted from about 60 to 50 million years ago forms Mull’s ‘stepped’ tablelands. Into these, at a later stage, intrusions of other ‘rocks formed by fire’ took place, forming the mountains of Mull’s famous Central Igneous Complex. Volcanic explosions and intense earthquakes shook Mull at that time. Now the lava has eroded and we are left with a huge granite base which can be clearly seen across the bay (from where you are standing) in the form of rocky cliffs.

Granite is formed within the crust of the Earth when Felsic magma, that is magma that is rich in Silica, cools down without reaching the surface. Because it remains beneath the surface as it is cooling, it forms large crystals ( individual crystals visible without need of a microscope). It has a minimum of 20% Quartz, up to 65% Feldspar and other minerals (such as Mica or Amphibole) are usually present and can make up to 25% of the total volume.

Mull’s final shape has largely been carved by huge glaciers which only melted away from Mull 10,000 years ago leaving deep ‘U’ shaped valleys between the mountains and long glaciated lochs both freshwater and marine.

Mull doesn’t have many precious gems at the surface, but geologists know that deep below Mull, in the earth’s mantle, there must be priceless minerals at this spot but the temperature at that depth would melt any drills probing for them! It has been known for sapphires to be found on some of the beaches!!!

Additional Hints (Decrypt)

Decryption Key

A|B|C|D|E|F|G|H|I|J|K|L|M
-------------------------
N|O|P|Q|R|S|T|U|V|W|X|Y|Z

(letter above equals below, and vice versa)


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