Exploring the Dolmen da Oração Complex in Florianópolis
On the island of Florianópolis in Brazil, a group of unusual granite formations has become the focus of archaeological and archaeoastronomical research. Located on and around Galheta Hill, the site includes the Dolmen da Oração, Pedra Virada, Menir Central and several other large stone formations.
The site is unusual because some of the formations have shapes and positions that have led researchers to investigate whether they were deliberately arranged or modified, while others appear to be natural granite formations. Research led by Adnir Ramos has proposed that several of the formations were used as astronomical markers, particularly for observing the changing position of the Sun throughout the year.
Adnir Ramos became interested in the archaeology and rock art of the region during the 1980s. In 1988, his observations of the Sun and Moon around Galheta Hill led him to begin investigating the relationship between the stones and the movements of the sky. Over time, this developed into a larger research project involving mapping, GPS measurements, aerial photography and astronomical software.
A 2002 study carried out with astronomer Germano Bruno Afonso examined the positions of the stones and proposed several possible astronomical alignments.
The Dólmen da Oração Trail was established in 2002, allowing visitors to explore the formations and learn about the research being carried out at the site. The route also includes a small museum with displays relating to the archaeology and rock art of the region.
The Astronomical Platform
One of the most interesting features of the site is the observation platform near the base of Galheta Hill. From here, several prominent stones higher up the hill can be viewed in relation to the horizon. According to the research carried out at the site, these stones create sightlines that correspond with the position of the rising Sun at different times of the year, including the solstices and equinoxes.
To investigate these proposed alignments, researchers have measured the positions of the stones and compared observations made in the field with astronomical calculations and mapping software such as Stellarium and Google Earth.
One of the clearest examples concerns the equinoxes. From a particular observation point, three stones create a small opening towards the horizon. Around the equinoxes, the rising Sun can be seen through this opening.
The Dolmen da Oração
The Dolmen da Oração is one of the most distinctive formations on Galheta Hill. A large granite slab rests on smaller stones, giving the formation the appearance of a dolmen. However, unlike the chambered dolmens found in Europe, there is no space to enter. The structure is relatively low, with the large slab sitting close to the ground.
The resemblance to a dolmen raises an important question about the formation. European dolmens are generally understood as prehistoric structures made from deliberately placed stones, often creating a chamber. At Galheta Hill, researchers are investigating whether the stones here were similarly arranged or modified by people, or whether their unusual shapes are entirely natural.
The name Dolmen da Oração, meaning “Dolmen of Prayer”, was given to the formation by Adnir Ramos and reflects his interpretation of the site. Whatever its origins, the formation becomes particularly interesting when viewed in relation to the other stones on the hill and the proposed astronomical alignments.
The Pedra Virada
Pedra Virada is another major formation within the complex. The large stone is supported by smaller blocks, giving it an appearance similar to a dolmen. Beneath it is a sheltered space with openings through which parts of the sky can be observed.
According to the research carried out at the site, these openings provide views of the rising Sun and particular stars at different times of the year. The Pleiades, the belt of Orion and Sirius are among the stars identified in these observations.
The position of the observer is important. Lying beneath the stone limits the view of the sky to the openings in the rock, creating a fixed view towards the horizon or the sky above. This has led researchers to investigate whether the formation and its openings were deliberately arranged to frame particular astronomical events, or whether these views are a result of the natural shape of the granite.
The Observatory of the Equinoxes
Another feature of the site is known as the Observatory of the Equinoxes. From a particular observation position, two stones create a small triangular opening towards the horizon. Around the equinoxes, the rising Sun can be seen through this opening.
There is also another observation point associated with sunset. The observer lies in front of a crescent shaped stone and looks through an opening towards the setting Sun.
These arrangements are particularly interesting because the observation points are quite specific. The alignment is not simply a case of finding a large stone that happens to face the Sun. The research describes particular positions from which the stones create a restricted view of the horizon.
That does not prove that prehistoric people constructed the arrangement for this purpose, but it provides a testable hypothesis.
This is where Galheta Hill becomes particularly relevant to archaeoastronomy. The question is not simply whether the Sun can be seen from the stones. It is whether the geometry of the stones, observation points and horizon shows patterns that are unlikely to be accidental.
The Central Menhir
The Central Menhir is a massive stone within the complex. The term “menhir” is used because of its upright form and its prominent position within the landscape. The stone is considered an energetic stone, and visitors have reported changes in their physical or emotional state when spending time in contact with it.
During our visit, Adnir Ramos invited us to place our foreheads against the stone. We did so, and shortly afterwards I experienced a strange phenomenon that I could not easily explain. It was unexpected and became one of the most memorable experiences of our visit. I describe exactly what happened in our article about Strange Phenomena at Ancient Sites.
The Marker Stone
There is a marker stone located beside the trail. It has a diagonal incision across its surface, accompanied by three small circular depressions below it. The markings are simple, but their combination gives the stone a distinctive appearance.
The marks have been interpreted locally as a Phoenician inscription. However, there is currently no convincing evidence to support this identification. The incised line does not correspond to a recognisable Phoenician letter, while the three circular depressions do not form a known Phoenician writing or numbering system. There is also no archaeological evidence for Phoenician activity at Galheta Hill that would provide a context for such an inscription.
The stone's position beside the trail is particularly interesting. Unlike the main formations, it is encountered while moving through the landscape. Its location may have been significant, perhaps marking a point along the route or drawing attention to a particular place.
The wider area has a long history of Indigenous occupation, and the archaeological landscape around Florianópolis contains numerous sites associated with Indigenous communities, including rock art and sambaquis. This provides an important context when considering markings on stones in the region. At the same time, there is currently no evidence linking this particular stone to a specific Indigenous group or establishing what the markings meant.
The Azure Jay
While exploring the site, we noticed an azure jay at the main stone complex. The bird did not seem particularly concerned by our presence and remained in the area as we moved between the stones, watching us from nearby.
At the time, we simply enjoyed the encounter. It was only later that we learned that the azure jay has a special place in the traditional beliefs of Indigenous peoples in southern Brazil. It appears in ancestral stories and carries spiritual significance, particularly in traditions associated with the forests of the region.
Learning about this afterwards gave the encounter another dimension. We had not known about these traditions when we saw the bird. It was simply an unexpected encounter with a bird that seemed unusually comfortable around us. It gave us the impression that we were being watched over by a keeper of the site.
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A Special Place
The Dolmen da Oração complex is a place where archaeology, astronomy, landscape and personal experience come together. There are still questions about whether particular stones were deliberately arranged or modified, but the research taking place here is gradually building a clearer picture of the site.
For us, the unusual formations, the views towards the horizon, the proposed astronomical alignments and the experience of spending time among the stones all contributed to making the place memorable.
There are other fascinating ancient stones in Florianópolis to explore. The more time we spent exploring the island, the more we realised that there was always another stone, another formation or another story waiting to be discovered.
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