Stone spheres of Costa Rica

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Stone spheres of Costa Rica
Stone sphere.jpg
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Location within Central America
Location Palmar Sur,  Osa, Puntarenas,  Costa Rica
Region Osa, Puntarenas
Coordinates 8°54′41″N83°28′39″W / 8.91139°N 83.47750°W / 8.91139; -83.47750
Periods500–1500 CE
Cultures Diquís culture
Official namePrecolumbian chiefdom settlements with stone spheres of the Diquís
Designated2014 (38th session)
Reference no. 1453
State Party Costa Rica
Region Latin America and the Caribbean
"Imagen Cosmica", a work on ancient mysticism, Costa Rican Art Museum, San Jose, Costa Rica, sculpture of Jorge Jimenez Deredia Escultura con esferas de J Jimenez Deredia.JPG
“Imagen Cósmica”, a work on ancient mysticism, Costa Rican Art Museum, San José, Costa Rica, sculpture of Jorge Jiménez Deredia
Pre-Columbian stone sphere, located at the University of Costa Rica as a symbol of tradition and ancient wisdom. Esfera Precolombina en Univ de Costa Rica.JPG
Pre-Columbian stone sphere, located at the University of Costa Rica as a symbol of tradition and ancient wisdom.

The stone spheres (or stone balls) of Costa Rica are an assortment of over three hundred petrospheres in Costa Rica, located on the Diquís Delta and on Isla del Caño. Locally, they are known as Las Bolas (literally The Balls). The spheres are commonly attributed to the extinct Diquis culture and are sometimes referred to as the Diquís Spheres. They are the best-known stone sculptures of the Isthmo-Colombian area. They are thought to have been placed in lines along the approach to the houses of chiefs, but their exact significance remains uncertain.

Petrosphere spherical man-made object of any size that is composed of stone

In archaeology, a petrosphere 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.

Costa Rica country in Central America

Costa Rica, officially the Republic of Costa Rica, is a country in Central America, bordered by Nicaragua to the north, the Caribbean Sea to the northeast, Panama to the southeast, the Pacific Ocean to the southwest, and Ecuador to the south of Cocos Island. It has a population of around 5 million in a land area of 51,060 square kilometers. An estimated 333,980 people live in the capital and largest city, San José with around 2 million people in the surrounding metropolitan area.

Isla del Caño island

Isla del Caño is a small island in the Bahia de Corcovado in Osa Costa Rica. It is on the Pacific Ocean side of Costa Rica, 10 miles (16 km) west of Punta Llorona on Península de Osa. It rises steeply to a flat top of 123 metres (404 ft) in height.


The Palmar Sur Archeological Excavations are a series of excavations of a site located in the southern portion of Costa Rica, known as the Diquís Delta. The excavations have centered on a site known as "Farm 6", dating back to the Aguas Buenas Period (300–800 CE) and Chiriquí Period (800–1550 CE).

In June 2014, the Precolumbian Chiefdom Settlements with Stone Spheres of the Diquis was added to the UNESCO list of World Heritage Sites. [1]

World Heritage Site place listed by the UNESCO as of special cultural or natural significance

A World Heritage Site is a landmark or area which is selected by the United Nations Educational, Scientific and Cultural Organization (UNESCO) as having cultural, historical, scientific or other form of significance, and is legally protected by international treaties. The sites are judged important to the collective interests of humanity.


The spheres range in size from a few centimetres to over 2 metres (6.6 ft) in diameter, and weigh up to 15 tons. [2] Most are sculpted from gabbro, [2] the coarse-grained equivalent of basalt. There are a dozen or so made from shell-rich limestone, and another dozen made from a sandstone. They appear to have been made by hammering natural boulders with other rocks, then polishing with sand. The degree of finishing and precision of working varies considerably. The gabbro came from sites in the hills, several kilometres away from where the finished spheres are found, though some unfinished spheres remain in the hills. They are used for decoration.

Gabbro A coarse-grained mafic intrusive rock

Gabbro is a phaneritic (coarse-grained), mafic intrusive igneous rock formed from the slow cooling of magnesium-rich and iron-rich magma into a holocrystalline mass deep beneath the Earth's surface. Slow-cooling, coarse-grained gabbro is chemically equivalent to rapid-cooling, fine-grained basalt. Much of the Earth's oceanic crust is made of gabbro, formed at mid-ocean ridges. Gabbro is also found as plutons associated with continental volcanism. Due to its variant nature, the term "gabbro" may be applied loosely to a wide range of intrusive rocks, many of which are merely "gabbroic".

Basalt A magnesium- and iron-rich extrusive igneous rock

Basalt is a mafic extrusive igneous rock formed from the rapid cooling of magnesium-rich and iron-rich lava exposed at or very near the surface of a terrestrial planet or a moon. More than 90% of all volcanic rock on Earth is basalt. Basalt lava has a low viscosity, due to its low silica content, resulting in rapid lava flows that can spread over great areas before cooling and solidification. Flood basalt describes the formation in a series of lava basalt flows.

Limestone Sedimentary rocks made of calcium carbonate

Limestone is a carbonate sedimentary rock that is often composed of the skeletal fragments of marine organisms such as coral, foraminifera, and molluscs. Its major materials are the minerals calcite and aragonite, which are different crystal forms of calcium carbonate (CaCO3). A closely related rock is dolostone, which contains a high percentage of the mineral dolomite, CaMg(CO3)2. In fact, in old USGS publications, dolostone was referred to as magnesian limestone, a term now reserved for magnesium-deficient dolostones or magnesium-rich limestones.

Geographic setting and location

The archaeological site of Palmar Sur is located in the southern portion of Costa Rica, known as the Diquís Delta, and in the southernmost part of the Puntarenas Province. The Diquís Delta is defined as the alluvial plain with the geographical boundaries of the Fila Grisera to the north and east, the Pacific Ocean to the west, and the Osa Mountains comprising the southern boundary.

The Site is located in Palmar Sur, southern Costa Rica. The site is located on approximately 10 hectares of property that was previously owned by the United Fruit Company in the alluvial plain of the Térraba River.

Palmar Sur human settlement in Costa Rica

Palmar Sur is a town in Costa Rica, located next to Palmar Norte in the Osa region of Puntarenas Province of Costa Rica. Palmar Norte and Palmar Sur are separated by the Rio Terraba. Palmar Sur has a regional airport that has daily flights arriving from San Jose on two regional airlines.

United Fruit Company American corporation

The United Fruit Company was an American corporation that traded in tropical fruit, grown on Latin American plantations, and sold in the United States and Europe. The company was formed in 1899, from the merger of Minor C. Keith's banana-trading concerns with Andrew W. Preston's Boston Fruit Company. It flourished in the early and mid-20th century, and it came to control vast territories and transportation networks in Central America, the Caribbean coast of Colombia, Ecuador, and the West Indies. Though it competed with the Standard Fruit Company for dominance in the international banana trade, it maintained a virtual monopoly in certain regions, some of which came to be called banana republics, such as Costa Rica, Honduras, and Guatemala.

Site description

View of the Farm 6 Archaeological site. Farm 6 archaeological site, Costa Rica.jpg
View of the Farm 6 Archaeological site.

The archaeological site of Farm 6 has been dated to the Aguas Buenas Period (300–800 CE) and Chiriquí Period (800–1550 CE). It was a multifunctional site accommodating a settlement and a cemetery, and remains of monumental architecture and sculpture are also present on the site. The monumental architecture consists of two mounds which were constructed with retaining walls made of rounded river cobbles and filled with earth. The site contains multiple locations where large stone spheres are found in situ. Additionally, since many of the stone spheres in the region were removed from their original locations and serve as landscape decoration, the site has become a storage location for spheres that have been returned to the National Museum. One of the neighboring towns to Farm 6 also had spheres or "esferas". They were called "zanahoriagas", for their more oval-like shape.[ citation needed ]

Pre-Columbian history

Palmar Sur airport park Pre-Columbian Stone Balls at Palmar Sur, Costa Rica.jpg
Palmar Sur airport park

The stones are believed to have been first created around the year 600, with most dating to after 1000 but before the Spanish conquest. The only method available for dating the carved stones is stratigraphy, but most stones are no longer in their original locations. The culture of the people who made them disappeared after the Spanish conquest. [3]

Post-contact history

The spheres were discovered in the 1930s as the United Fruit Company was clearing the jungle for banana plantations. [3] Workmen pushed them aside with bulldozers and heavy equipment, damaging some spheres. Additionally, inspired by stories of hidden gold, workmen began to drill holes into the spheres and blow them open with sticks of dynamite. Several of the spheres were destroyed before authorities intervened. Some of the dynamited spheres have been reassembled and are currently on display at the National Museum of Costa Rica in San José.

The first scientific investigation of the spheres was undertaken shortly after their discovery by Doris Stone, a daughter of a United Fruit executive. These were published in 1943 in American Antiquity , attracting the attention of Samuel Kirkland Lothrop [4] of the Peabody Museum at Harvard University. [5] In 1948, he and his wife attempted to excavate an unrelated archaeological site in the northern region of Costa Rica. [6] The government had just disbanded its professional army, and the resulting civil unrest threatened the security of Lothrop's team.[ citation needed ] In San José he met Doris Stone, who directed the group toward the Diquís Delta region in the southwest ("Valle de Diquís" refers to the valley of the lower Río Grande de Térraba, including the Osa Canton towns of Puerto Cortés, Palmar Norte, and Sierpe [7] ) and provided them with valuable dig sites and personal contacts. Lothrop's findings were published in Archaeology of the Diquís Delta, Costa Rica 1963.

In 2010, University of Kansas researcher John Hoopes visited the site of the Stone Spheres to evaluate their eligibility for protection as a Unesco World Heritage Site. [8]

Historical background

Remnants of UFCO occupation in Palmar Sur UFCO remnants.jpg
Remnants of UFCO occupation in Palmar Sur

Before the arrival of the Companía Bananera de Costa Rica, a branch of the United Fruit Company, and banana plantations in the 1930s, vegetation in this area offered a great deal of biodiversity in both plant and animal resources. Resources available to Precolumbian inhabitants in this alluvial plain consisted of riverine and ocean resources, including mangrove forests located in the Terraba and Sierpe Rivers.

Modern Landscape of Palmar Sur, Costa Rica Palmar Sur, Costa Rica (2007).jpg
Modern Landscape of Palmar Sur, Costa Rica

The rich alluvial soils of this region facilitated historical agriculture since the 1930s. The United Fruit Company dominated this southern region with banana plantations as early as the 1920s in Parrita and Quepos. The UFCO entered Palmar Sur in the 1930s under the name of Companía Bananera de Costa Rica in an effort to avoid antimonopoly legislature. [9] Today the landscape is still carved into agricultural fields which are owned by co-ops and consist of plantain, banana, and palm plantations.

Early researchers in the region

Scientific research in the alluvial plain, particularly on United Fruit Company properties, began in the 1940s with the work of Doris Zemurray Stone and Samuel Lothrop. Lothrop's work focused on excavation at a handful of sites, one being Farm 4. His work aimed to document all archaeological sites containing "in situ" stone spheres, to record the number of spheres and their dimensions, and to make detailed maps illustrating both their arrangement and alignments.

After the work of Lothrop and Stone, research in the area took a hiatus for nearly fifty years. In the 1990s, Claude Baudez and a team of researchers set out to establish a ceramic chronology of the region by observing the change in ceramic styles over time. [10] This was accomplished by examining the drainage ditches that were cut into the landscape by the UFCO. Research carried out by Ifigenia Quintanilla, under the direction of the MNCR from 1991–1996 was performed in the region under the project titled "Man and Environment in Sierpe-Terraba" focusing on settlement patterns, occupational sequences, and resources utilized in the region. [11]

Francisco Corrales and Adrian Badilla, archaeologists with the Museo Nacional de Costa Rica, have performed continuous research in the region since 2002. Their research began in 2002 and focused on four archaeological sites in the region containing stone spheres and of which comprise a "circuit". These sites include Grijalba, Batambal, El Silencio, and "Farm 6". The purpose of the project was to assess the cultural significance of the sites, to protect the cultural heritage, in addition to beginning research and studies at the sites. [12] Corrales and Badilla produced a booklet entitled El Paisaje Cultural del Delta del Diquís which provides a quick overview on the history of the Diquís Delta, the history of banana plantations and the UFCO, the natural environment, archaeological sites in the region, and the importance of the Diquís region as an UNESCO World Heritage Site. [13] Research has continued in the region by Corrales and Badilla focusing on the archaeology and the Precolumbian political structure in the Diquís Delta. Research emphasis was on chiefdoms and their associated archaeological indicators. Their objectives were to study the archaeological sites containing stone spheres in the Diquís Subregion to gain an understanding of community configuration, activity areas, sequences of occupation, and the recording of monumental architecture. [14]

Current research

Research is currently ongoing at the "Farm 6" site under the direction of archaeologists at the Museo Nacional de Costa Rica. The first field season in which archaeological excavations were undertaken was in 2005. Objectives during this field season included defining the area in which two mounds were located, sphere alignments, and various excavations associated with mound 2. In 2007, as second field season was undertaken focusing on archaeological excavations of Mound 1. During this field season, a stone sphere was discovered "in situ" in association with the mound.


Archaeo-tourism is a concept that is still relatively new in Costa Rica. To date, the national monument of Guayabo de Turrialba is primarily the only archaeological site open for tourism. Tourism on a smaller scale is occurring at the site of Farm 6 but is open to visitors upon paying a nominal fee to tour the museum display and then tour the grounds, viewing some of the discovery sites. It is no longer necessary to have an appointment. Future plans of the MNCR are to open the site to tourism on a larger scale and to include other sites nearby in the region.


Numerous myths surround the stones, such as they came from Atlantis, or that they were made as such by nature. Some local legends state that the native inhabitants had access to a potion able to soften the rock. Limestone, for example, can be dissolved by acidic solutions obtained from plants. Research led by Joseph Davidovits of the Geopolymer Institute in France has been offered in support of this hypothesis. [15] However, most of the spheres were created from gabbro, an acid-resistant igneous rock. [16]

In the cosmogony of the Bribri, which is shared by the Cabecares and other American ancestral groups, the stone spheres are “Tara’s cannon balls”. Tara or Tlatchque, the god of thunder, used a giant blowpipe to shoot the balls at the Serkes, gods of winds and hurricanes, in order to drive them out of these lands.

It has been claimed that the spheres are perfect, or very near perfect in roundness, although some spheres are known to vary over 5 centimetres (2.0 in) in diameter. Also, the stones have been damaged and eroded over the years, and so it is impossible to know exactly their original shape. A review of the way that the stones were measured by Lothrop reveals that claims of precision are due to misinterpretations of the methods used in their measurement. Although Lothrop published tables of ball diameters with figures to three decimal places, these figures were actually averages of measurements taken with tapes that were nowhere near that precise. [17]

See also

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The Diquis culture was a pre-Columbian indigenous culture of Costa Rica that flourished from AD 700 to 1530. The word "diquís" means "great waters" or "great river" in the Boruca language. The Diquis formed part of the Greater Chiriqui culture that spanned from southern Costa Rica to western Panama.

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Carlos Aguilar Piedra was a prominent Costa Rican archaeologist on the faculty of the University of Costa Rica. He is often referred to as "the grandfather of Costa Rican archaeology" for his significant work at Guayabo de Turrialba and other sites in the Central Highlands region of that country.

Palmar Norte is a town in Costa Rica, located next to Palmar Sur in the Osa region of Puntarenas Province. Although small, the town serves as a major agricultural center and as an important transit point for travelers to the Palmar Sur Airport. It is also home to the stone spheres of Costa Rica. Palmar Norte and Palmar Sur are separated by the Rio Terraba. The river overflowed during Tropical Cyclone Nate in October 2017, sweeping away houses and leaving 200 residents homeless.

Claude-François Baudez French Mayanist, archaeologist and iconologist

Claude-François Baudez was a French Mayanist, archaeologist and iconologist. He was honorary director of research at the Centre national de la recherche scientifique, a specialist on the rituals and beliefs of Mesoamerica, particularly of the Maya civilisation.


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