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Siccar Point, Scottish Borders (Berwickshire), Scotland, UK
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UK Grid Reference: NT813709
Latitude: 55°55'51"N
Longitude: 2°17'57"W
 
 
The angular unconformity at Siccar Point is one of the world’s most celebrated geological localities on account of its role in establishing that the earth is of great age. Less well known is the fact that it is also a mineral locality, as the rocks are cut by thin veins of barite, providing a convenient justification for including this famous site on mindat. Collectors should note, however, that owing to its great historical importance it is a Site of Special Scientific Interest (SSSI), and hammering is unlikely to be appreciated! The barite is of poor quality anyway, although it does exhibit cockscomb habit when crystallised in small cavities.

It is the role the locality played in the early development of the earth sciences that makes it so special. Gentleman farmer and amateur geologist, James Hutton visited here in 1788, with his friends John Playfair and Sir James Hall. Hutton himself seems to have been rather blasé about it. He had already found other examples of unconformities in Scotland, and had read descriptions of continental examples. His friends, however, were impressed. Playfair was later to write: “What clearer evidence could we have had of the different formation of these rocks, and of the long interval which separated their formation, had we actually seen them emerging from the bosom of the deep? …. The mind seemed to grow giddy by looking so far into the abyss of time.” (Playfair, 1805). Ever since the locality has been cited as proof of the great age of the earth, and is a Mecca for geology students. For a detailed account of the history the reader is referred to Montgomery (2003).

The accompanying photos show what they found. As explained in Moreton (2011), “The upright beds are Silurian greywackes and shales. Hutton knew these must have been deposited originally as horizontal layers. Overlying them at almost a right angle are gently dipping red Devonian sandstones. The bottom layer of these is a breccia full of broken fragments of the underlying Silurian rocks in a red sandy matrix. This, Hutton realised, was an ancient land surface where once the upright Silurian strata had been exposed and eroded, and onto which the red sandstones were deposited. These rocks indicated a sequence of events far longer than the Biblical 6000 years. Firstly, rocks had to be eroded to generate the sediments deposited on an ancient sea floor. These were then hardened into rock, folded until the beds were upright, elevated and eroded to create a land surface. Onto this eroded surface was deposited another generation of sediments, creating the beds of red sandstone. These too hardened into rock, were tilted slightly and eroded to expose them, and the underlying rocks, once more.” For a fuller description and review of the geological literature on Siccar Point see Moreton (2011), and also the photos and their captions here.

Links to the references are provided below.

Mineral List

Baryte


1 entry listed. 1 valid mineral.

The above list contains all mineral locality references listed on mindat.org. This does not claim to be a complete list. If you know of more minerals from this site, please register so you can add to our database. This locality information is for reference purposes only. You should never attempt to visit any sites listed in mindat.org without first ensuring that you have the permission of the land and/or mineral rights holders for access and that you are aware of all safety precautions necessary.

References

Montgomery, K. (2003) “Siccar Point and Teaching the History of Geology”. Journal of Geoscience Education, vol. 51(5), p. 500-505.

Moreton, S. (2011) “Rocks in their heads”. The Skeptic, vol. 31(2), p. 52-54.

Playfair, J. (1805) Biographical Account of the late Dr. James Hutton, Transactions of the Royal Society of Edinburgh, V(III), 39-99.

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Copyright © Jolyon Ralph and Ida Chau 1993-2014. Site Map. Locality, mineral & photograph data are the copyright of the individuals who submitted them. Site hosted & developed by Jolyon Ralph. Mindat.org is an online information resource dedicated to providing free mineralogical information to all. Mindat relies on the contributions of thousands of members and supporters. Mindat does not offer minerals for sale. If you would like to add information to improve the quality of our database, then click here to register.
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