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JOURNEY OF DISCOVERY

A cache by Fungimanforager Send Message to Owner Message this owner
Hidden : 2/18/2013
Difficulty:
5 out of 5
Terrain:
4 out of 5

Size: Size: other (other)

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Geocache Description:

As an EarthCache, there is no “box.” You discover something about the geology of the area. For more info about EarthCache's take a look at www.earthcache.org



This cache was placed with the kind permission of :

SNH designates SSSIs under the Nature Conservation (Scotland) Act 2004. SSSIs are protected by law. It is an offence for any person to intentionally or recklessly damage the protected natural features of an SSSI.

JOURNEY OF DISCOVERY





UAMH NAN CAILLEACH

At first glance this earthcache may look a little daunting but fear not, read on? Drive to Carsaig and park near to the jetty taking care not to block it. PRINT OFF CLUE PHOTO'S

Carsaig Bay is one of the most scenically beautiful locations on the south coast of Mull and a haven for geologists, walkers and wildlife enthusiasts alike. The hamlet of Carsaig lies enclosed in a natural amphitheatre of towering basalt cliffs, producing some of the highest and most spectacular coastal scenery on the island.

I would like to invite you to visit a number of geological sites as as you travel West along this coastal path and rocky beach, as you head to the posted co-ords which are for the Nun's Cave. The Waypoints are in the order that you may find them on route.

If you have the time you may wish to continue your journey and follow the route description to Carsaig Arches.

GLOSSARY OF SOME OF THE GEOLOGICAL FEATURES THAT MAY BE FOUND ALONG THIS ROUTE

Basalt - fine-grained, mafic, igneous rock composed predominantly of ferromagnesian minerals and with lesser amounts of calcium-rich plagioclase feldspar.

Basalt (vesicular) - Vesicular texture is a volcanic rock texture characterized by a rock being pitted with many cavities (known as vesicles) at its surface and inside.

Basalt (amygdaloidal) - Having a cellular or vesicular structure: said of lava, in which spherical or almond-shaped cavities were formed by the expansion of steam contained in the rocks at the time of its consolidation, and which have later become filled with various minerals, especially quartz, calcite, or the zeolites.

Cone Sheets - A dyke shaped in cross-section like a cone dipping inwards to a central pluton. This characteristic form is usually explained by reference to a stress field, shaped like an inverted umbrella, generated by the parent pluton at depth.

Dykes - A type of sheet intrusion referring to any geologic body that cuts discordantly across.

Fossils - Mineralised or otherwise preserved remains or traces (such as footprints) of animals, plants, and other organisms.

Ovoid Concretions (Doggers) - A large, calcareous nodule or concretion. Spherical or sub-spherical in shape.

Pepperite - A heterogeneous deposit composed of dark basalt fragments and light-colored sediment

Quartz filled Vugs - Small cavity in a rock filled or lined with crystals/minerals that are different from the host rocksills

Tachylite - A black, green, or brown volcanic glass formed from basaltic magma. Also known as basalt glass; basalt obsidian; hyalobasalt; jaspoid; sordawalite; wichtisite.

Xenolith - A rare earth phosphate mineral, whose major component is yttrium orthophosphate (YPO4)



PRINTING THE INFORMATION BELOW FOR REFERENCE AND THE ROUTE DESCRIPTION MAY HELP YOU?

LOGGING REQUIREMENTS

Below I have described several features and several locations/waypoints; the location (Lat Long) does not correspond to the order of the descriptions below.

  1. Is to visit FIND AND PHOTOGRAPH at least FOUR (4) of the indicated sites of your choice PLUS THE CAVE.


  2. Include a photo of each site that you visit in your log without disclosing its location.


  3. Email to me through my profile which photo matches which explanation/waypoint, i.e. photo ‘1’ in log equals explanation ‘5’ Etc.


  4. Visit Nuns Cave and estimate the width of the entrance, the depth and the maximum height.


  5. Include a picture of one or more of the crosses carved on the wall of the cave in your log, if you cannot find the crosses, improvise your photo at the mouth of the cave for your log.


    YOUR CHOICE OF SITES TO VISIT,PHOTOGRAPH AND MATCH UP




    1. Isolated pillars of sandstone probably arose through a contrast in the cementing by carbonate, whereby the softer, less well-cemented sandstone has been eroded away completely. Bedding features in the sandstone are well displayed.



    2. The scallop-like fossil in this view is a Pecten, and it is in the Pabay Shale, of Jurassic age. Pectens are very common in the fossil record. There is also a small v-shaped bivalve, probably a small Pinna, at upper left.



    3. This ridge of rock running out to seaward is a much eroded sill formed by igneous material intruded between beds of Jurassic sediment.



    4. This is a large fossil bivalve. There are several specimens in the Pabay Shale, which is of Jurassic age.
 The surface of this bed of Pabay Shale contains several belemnites.

      These are the fossil skeletons of a squid-like marine creature that lived in Jurassic times. The longest one here is about four inches (10 centimetres) long.



    5. The brown lumps are carbonate concretions which have formed in the Scalpay Sandstone, then been exposed by erosion and are themselves being weathered to a honeycomb surface. Some of them have split into two or more sections.



    6. A Curved sill. The saucer shape of the igneous body on the beach is probably the result of the magma that formed it being intruded between curving beds in the crust of the Earth.



    7. CAVE



    8. The ridges crossing the flat shoreline rocks are igneous dykes intruded long after their host rocks were formed.



    9. View of cliffs with the Jurassic Scalpa Sandstone at the foot and the basalt columns of the Staffa Formation above. Sròn nam Boc means 'the buck's nose', and it is applied to the crest of the ridge here. There are also Toarcian black shales, Greensand and Cretaceous sediments, but these are not easy to pick out from sea level, and it requires a risky scramble to get close to them. No climbing required here for this cache.




    10. Rock succession. The rocks at beach level and in the lower cliffs are Jurassic sandstones, but in this view the overlying basalt lava flows, some with well-developed prismatic jointing, are also also displayed. The contact between rocks which are around 180 million years old and the basalts of around 58 million years marks a considerable leap in Earth history.


    11. This is a large fossil bivalve. There are several specimens in the Pabay Shale, which is of Jurassic age. This specimen is partly under the water of a small rock pool.



    12. Dyke an igneous intrusion that cuts across the sedimentary deposits on the beach.


    13. Cross-cutting Veins There are three veins on the surface of this pitchstone rock. A broad one runs from upper left of centre to lower right of centre. This is cut by a narrower vein running from lower left of centre towards the top right corner. Both of these veins are cut by a third one running straight across, half-way up this view. Thus it is possible to tell which is the oldest and which the youngest. This technique enables geologists to determine the relative of ages of rocks at all scales from tiny veins like these to large dykes which can continue for many miles.





    Click here FOR THE ROUTE DESCRIPTION.


    Click hereTO VIEW THE SNH FOSSIL CODE.

    Click hereTO VIEW COMMON FOSSILS, ROCKS & MINERALS.

    Click hereTO VIEW GEOLOGICAL FIELDWORK CODE.

    Click here TO VIEW, Ancient Carved Crosses inside the Nuns cave,Carsaig arches footpath,Ross,Isle of Mull,Highlands,West. Photo+ info.

    Click here Archaeological Notes.

    FURTHER READING AND REFERENCE:

    For more historical info: see: RCAHMS  Argyll Volume 3  (Her Majesty's Stationery Office Edinburgh 1980) ISBN 0 11 491591 1

    Click here For Interactive British Stratification Tables (OU).

    Click here Geological Conservation Review Carsaig Bay.

    Click here Marine Bivalve Shells of the british Isles .


    Click here British Lower Jurassic stratigraphy

    Click here Dykes and Sills Formation

    Click hereTO VIEW GLOSSARY OF GEOLOGY


I have earned GSA's highest level:

Additional Hints (Decrypt)

CEVAG BSS GUR EBHGR QRFPEVCGVBA NAQ SBYYBJ VG

CEVAG BSS PYHR CUBGB'F

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)



 

Find...

26 Logged Visits

Found it 23     Write note 2     Publish Listing 1     

View Logbook | View the Image Gallery of 170 images

**Warning! Spoilers may be included in the descriptions or links.

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Rendered From:Unknown
Coordinates are in the WGS84 datum

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