Stone ball
{{Other uses}}
{{short description|Spherical man-made artifact composed of stone}}
File:Kelvingrove Art Gallery and MuseumDSCF0239 11.JPG, in Kelvingrove Art Gallery and Museum, Glasgow]]
In archaeology, a stone ball or petrosphere (from Greek πέτρα (petra), "stone", and σφαῖρα (sphaira), "ball") is the name for any spherical man-made object of any size that is composed of stone. These mainly prehistoric artifacts may have been created or selected, but altered in some way to perform their specific function, including carving and painting.
File:Alignment Diquis Stone Spheres Museo Nacional CRI 01 2020 1855.jpg in Museo Nacional de Costa Rica.]]
Several classes of petrospheres exist, such as:
- the stone spheres of Costa Rica,
- painted pebbles from Scotland,
- stone charms from Scotland and sandstone balls from such sites as Traprain Law,Rees, Thomas & Hunter, Fraser (2000). Archaeological excavation of a medieval structure and an assemblage of prehistoric artefacts from the summit of Traprain Law, East Lothian. 1996 - 7. P.S.A.S. 130, P. 413 - 440.
- the carved stone balls, which are mainly from Scotland, although they have also been found in Cumbria and Ireland,
- and carved stone shot for cannons and trebuchets.
Naturally formed stone balls, such as concretions and spherulites, have been at times misidentified as petrospheres. For example, fringe archaeologists and advocates of prehistoric extraterrestrial visitors have repeatedly argued that the stone balls, which range in diameter from {{cvt|0.61|to|3.35|m}}, found around Cerro Piedras Bola in the Sierra de Ameca, between Ahualulco de Mercado and Ameca, in Jalisco, Mexico, are petrospheres{{Citation needed|date=October 2021}}. However, these natural stone balls are megaspherulites that have been released by erosion from a 20- to 30-million-year-old ash flow tuff, which originally enclosed them and in which they formed. The proponents of these stone balls being petrospheres base their arguments on the false claims that all of these spheres are perfectly round, that they are composed of granite, and that natural processes cannot produce stone balls{{Citation needed|date=October 2021}}. Similarly, cannonball concretions, i.e. those found along the Cannonball River in North Dakota and near Moeraki, South Island, New Zealand, also have been misidentified as petrospheres{{Citation needed|date=October 2021}}.
Palaeolithic shaped stone balls
File:Shaped stone balls from Qesem Cave.png, {{circa}} 420,000–200,000 years old.]]
Shaped stone balls are found at Palaeolithic sites across Africa, Asia, and Europe, associated with Oldowan ({{Circa|}} 2.6 million – 1.7 million years old), Acheulean ({{Circa|}} 1.76 million – 130,000 years old), and African Middle Stone Age ({{Circa|}} 280,000–50,000 years old) stone tool industries.{{Cite journal|last1=Assaf|first1=Ella|last2=Caricola|first2=Isabella|last3=Gopher|first3=Avi|last4=Rosell|first4=Jordi|last5=Blasco|first5=Ruth|last6=Bar|first6=Oded|last7=Zilberman|first7=Ezra|last8=Lemorini|first8=Cristina|last9=Baena|first9=Javier|last10=Barkai|first10=Ran|last11=Cristiani|first11=Emanuela|date=2020-04-09|title=Shaped stone balls were used for bone marrow extraction at Lower Paleolithic Qesem Cave, Israel|journal=PLOS ONE|language=en|volume=15|issue=4|pages=e0230972|doi=10.1371/journal.pone.0230972|pmid=32271815|pmc=7145020|bibcode=2020PLoSO..1530972A|issn=1932-6203|doi-access=free}}
The function of shaped stone balls is still debated. Some archaeologists argue that they were deliberately shaped by humans to use as tools; others that they are byproducts of the use of rocks for other purposes.
See also
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References and bibliography
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External links
{{wikibooks|A Researcher's Guide to Local History Terminology}}
{{Commonscat|Stone spheres}}
- [http://ads.ahds.ac.uk/catalogue/adsdata/PSAS_2002/pdf/vol_004/4_211_224.pdf Scottish Stone charms] {{Webarchive|url=https://web.archive.org/web/20070611153419/http://ads.ahds.ac.uk/catalogue/adsdata/PSAS_2002/pdf/vol_004/4_211_224.pdf |date=2007-06-11 }}
- Ruffell, W.L., 1996, [https://web.archive.org/web/20070920190941/http://www.riv.co.nz/rnza/hist/gun/smooth4.htm The Gun - Smoothbore Era 1550-1860: Projectiles] Royal New Zealand Artillery Old Comrades' Association, New Zealand.
- Hoopes, J.W., 2005, [https://web.archive.org/web/20070627180405/http://web.ku.edu/~hoopes/balls/ The Stone Balls of Costa Rica] University of Kansas, Lawrence, Kansas.
- Hunterian Museum and Art Gallery, nd, [http://www.hunterian.gla.ac.uk/collections/museum/online_exhibitions/stones/objects/objects.shtml Carved Stone Balls] A gallery of carved stone ball photographs & information
- Marischal Virtual Museum, nd, [http://www.abdn.ac.uk/virtualmuseum/index.php?page=topic&topic=ball,..carved..stone&case=n06&first=7&last=18&roomlocation=ng ball, carved stone] Aberdeen Museum's virtual gallery of their Carved Stone balls
- A Researcher's Guide to Local History terminology
- [http://www.megalithic.co.uk/article.php?sid=147 Carved Stone Balls of Skara Brae]