Gruta das Torres
Encyclopedia
The Gruta das Torres is a lava cave
, a geological formation of volcanic origin formed from the flow and cooling of subterranean magma rivers. This formation is located outside the parish of Criação Velha
, in the municipality of Madalena
, on the western flanks of the island of Pico
. The cave system formed from a series of pahoehoe lava
flows which originating from the Cabeço Bravo parasitic cone
about 500 to 1500 years ago. The caves are a group of interconnected lava tube
s between 0.5–22 meters (2–72 ft) width, created from both pahoehoe and aa types of lavas generated during different geological periods. It has a height between 1.1 and 15 meters (3.6–49 ft) and is located at an elevation of300 metres (984.3 ft). With an estimated length of over 5.2 km (3.2 mi) it is the longest lava cave in the Azores. Access to the cave was managed by the Mountaineering Association (“Os Montanheiros” – Núcleo da Ilha do Pico). Starting in 2011 , AZORINA, SA took over the management and organization of the cave.
The cave doesnt have a date of discovery but the first cientific exploration was in 1990. The cave's uniqueness lies in its impressive drainage pattern, which can be shown by the presence of more than seven layers on the walls, with lateral benches and three cornices. Gruta das Torres is one of the 17 caves (out of 28 found here) in Pico Island of the 30 caves chosen for Azores as a whole (from a over all list of for inscription under the UNESCO
List of World Heritage Sites proposed by the Government of Azores
.
declared the cave a regional natural monument on March 18, 2004 (Monumento Natural Regional DLR N.° 6/2004/A), the second regional natural monument to gain such a distinction, and to be honored for its unique geological setting and its length in Azores. Following this, a visitor center was planned and built as a facility for visitors. It is also inferred that the caves are a part of the volcanic phenomenon in the mountains of Azores that occurred about 1000 years ago.
in Madalena
in the western-mid part of the island of Pico, in the central-south of the Azores. The Torres Grotto is one of 28 larger caves and eight pits discovered in the island of Pico, which has the largest number of caves of any island in the Azores. Most of these caves lie in the western half of Pico Island.
The lava tunnel is at a ten-minute walking distance to the south of Madelena. A sign post near Criacao Vella directs to the Grutas Das Torres. The cave has two entrances. The first entrance is open to the sky or a day lighted roof at one end of the tunnel. The other entry is a tunnel cavern opening which is inferred to have been formed due a slump in the roof. The tunnel has clear pahoehoe lava in some reaches while in some other reaches the roof has collapsed with large lava blocking the tunnel route making access hazardous and narrow. Lava gutters are also seen. A number of secondary tunnels also have impressive geological formations. The lava tubes have picturesque formations of stalactites (lavacicle
s), stalagmites, lava
, lava bench
es and side balls or balls of lava. Considering the large size of the cave, with further scientific studies more faunal species may be discovered.
The liquid lava that dripped from the roof of Gruta das Torres has formed into picturesque stalactite and stalagmite and also in several other formations and shapes. Inside the tunnel, it is humid as water drips from the roof and a constant temperature of 16 °C (60.8 °F) is recorded throughout the year. However, the entrance has a slightly higher temperature. The total drop is approximately 200 m (656.2 ft).
The tunnels formed within a pahoehoe type lava flow. The top of the flow cooled against the air and formed a solid crust, while beneath it the liquid lava continued to move. As the amount of liquid lava passing through them decreased, the tunnels emptied. Silica oxide is also seen in walls of the cave in some stretches of the cave. At the main entrance, after passing through the ‘Algar da Ponte’ ("Algar Bridge"), there is an avenue of trees. Some forms of plant life like ferns, mosses and lichens are also noted at the portal, floor and walls of the cave opening.
Deep inside, in the darker regions of the cave, mold
, bacteria
and insects have been identified. The troglobite
faunal species found, typical of such caves, are the endemic species of Trechus Pico Machado and Cixius azopicavuz Hoch.
for inscribing under the UNESCO World Heritage List. A Working Group on Volcanic Caves of Azores supported by the Azorean Speleological Inventory and Classifying System database has identified 30 Volcanic Caves of Rank A, which are located in the Graciosa
, Pico
, São Jorge, São Miguel
and Terceira islands for inclusion in the UNESCO List. Of these 30 volcanoes identified for UNESCO recognition, Pico island has the maximum number of 17 volcanic caves in the proposal, which includes the Gruta das Torres cave. The selection criteria for inclusion of the caves in the list was based on the scientific value, tourism prospects, approach conditions, perceived threats, data base and conservation standing.
and Portuguese
give details about the cave. As of 2011, the tours are scheduled for 10:30, 12:00, 13:30, 15:00 and 16:30 for the months of higher visitation (15th June to 15th September).
The Visitors' Support Centre at the entrance to the cave has innovative architectural features – “a circular sweep and a linear spatial organization – a sequence of programmatic spaces that prepare visitors for the spectacle below.” It was awarded the "European Union Prize for Contemporary Architecture Mies van der Rohe Award 2007", in Barcelona
. It was a formal award presented by the European Union
, in association with the Mies van der Rohe Foundation.
The innovative construction of the visitor center ensures that the cave entrance has full exposure to the skylight. To achieve this, the layout has incorporated techniques of local building architecture in the form of 'currais de figueira' meaning 'fig tree walls” structure. Such walls used to be part of the vineyards in the region as protection from wind and seawater. This front elevation forms the natural southern part of the building. The wall which is 1.8 metres (5.9 ft) in height has an “open-weave structure” or undulating structure to permit natural lighting to the entire building, thus eliminating provision of windows. It also provides protection to the entrance into the tunnel. The building also incorporates a design which provides uniform illumination of the interior. It eliminates the need for other openings. Except for the wall at the entrance, the main building is painted with a waterproof black colour finish to match with the colour and texture of the vitrified lava inside the cave.
Lava cave
A lava cave is any cave formed in volcanic rock, although in typical usage it is reserved for caves formed by volcanic processes, which are more properly termed volcanic caves...
, a geological formation of volcanic origin formed from the flow and cooling of subterranean magma rivers. This formation is located outside the parish of Criação Velha
Criação Velha
Criação Velha is a civil parish in the municipality of Madalena on the island of Pico in the Azores. Census records for the community in 2001, found about 818 inhabitants in residence in the parish.- History :...
, in the municipality of Madalena
Madalena (Azores)
Madalena is a municipality along the western coast of the island of Pico, in the Portuguese Azores. The municipality has a population of 6,184 inhabitants and a total area of 147.1 km²...
, on the western flanks of the island of Pico
Pico Island
Pico Island , is an island in the Central Group of the Portuguese Azores noted for its eponymous volcano, Ponta do Pico, which is the highest mountain in Portugal, the Azores, and the highest elevation of the Mid-Atlantic Ridge...
. The cave system formed from a series of pahoehoe lava
Lava
Lava refers both to molten rock expelled by a volcano during an eruption and the resulting rock after solidification and cooling. This molten rock is formed in the interior of some planets, including Earth, and some of their satellites. When first erupted from a volcanic vent, lava is a liquid at...
flows which originating from the Cabeço Bravo parasitic cone
Satellite cone
A parasitic cone is the cone-shaped accumulation of volcanic material not part of the central vent of a volcano. One forms by eruptions from fractures on the flank of the volcano. These fractures occur because of the flank of the volcano is unstable...
about 500 to 1500 years ago. The caves are a group of interconnected lava tube
Lava tube
Lava tubes are natural conduits through which lava travels beneath the surface of a lava flow, expelled by a volcano during an eruption. They can be actively draining lava from a source, or can be extinct, meaning the lava flow has ceased and the rock has cooled and left a long, cave-like...
s between 0.5–22 meters (2–72 ft) width, created from both pahoehoe and aa types of lavas generated during different geological periods. It has a height between 1.1 and 15 meters (3.6–49 ft) and is located at an elevation of300 metres (984.3 ft). With an estimated length of over 5.2 km (3.2 mi) it is the longest lava cave in the Azores. Access to the cave was managed by the Mountaineering Association (“Os Montanheiros” – Núcleo da Ilha do Pico). Starting in 2011 , AZORINA, SA took over the management and organization of the cave.
The cave doesnt have a date of discovery but the first cientific exploration was in 1990. The cave's uniqueness lies in its impressive drainage pattern, which can be shown by the presence of more than seven layers on the walls, with lateral benches and three cornices. Gruta das Torres is one of the 17 caves (out of 28 found here) in Pico Island of the 30 caves chosen for Azores as a whole (from a over all list of for inscription under the UNESCO
UNESCO
The United Nations Educational, Scientific and Cultural Organization is a specialized agency of the United Nations...
List of World Heritage Sites proposed by the Government of Azores
Azores
The Archipelago of the Azores is composed of nine volcanic islands situated in the middle of the North Atlantic Ocean, and is located about west from Lisbon and about east from the east coast of North America. The islands, and their economic exclusion zone, form the Autonomous Region of the...
.
Discovery
The Gruta das Torres's doesnt have a date of discovery but the first cientific exploration was in 1990. Between March 28 and April 23, 1991, a "three dimensional braided system" was documented by a team of speleologists when the cave was recorded as the longest lava tube in Azores with the explored length of 3350 meters. The total length is still uncertain as parts of the tube have not been accessed yet, but it is estimated as over 5200 meters. Declared a national natural monument by the Portuguese Environmental Department, the Azores Regional GovernmentAzores
The Archipelago of the Azores is composed of nine volcanic islands situated in the middle of the North Atlantic Ocean, and is located about west from Lisbon and about east from the east coast of North America. The islands, and their economic exclusion zone, form the Autonomous Region of the...
declared the cave a regional natural monument on March 18, 2004 (Monumento Natural Regional DLR N.° 6/2004/A), the second regional natural monument to gain such a distinction, and to be honored for its unique geological setting and its length in Azores. Following this, a visitor center was planned and built as a facility for visitors. It is also inferred that the caves are a part of the volcanic phenomenon in the mountains of Azores that occurred about 1000 years ago.
Geography
The Gruta das Torres is located on the lower western slope of Mount Pico, located in the parish of Criação VelhaCriação Velha
Criação Velha is a civil parish in the municipality of Madalena on the island of Pico in the Azores. Census records for the community in 2001, found about 818 inhabitants in residence in the parish.- History :...
in Madalena
Madalena (Azores)
Madalena is a municipality along the western coast of the island of Pico, in the Portuguese Azores. The municipality has a population of 6,184 inhabitants and a total area of 147.1 km²...
in the western-mid part of the island of Pico, in the central-south of the Azores. The Torres Grotto is one of 28 larger caves and eight pits discovered in the island of Pico, which has the largest number of caves of any island in the Azores. Most of these caves lie in the western half of Pico Island.
Formation
The Gruta das Torres is located on the slope of Pico, further down than Furna de Frei Matias, a large cave inside Pico's cone. The largest lava tube, cited by various sources to either be the longest or second longest in Azores formed by a volcanic eruption originating in Cabeço Bravo. The main part of the tunnel is fairly large with a height of 15 meters in places, although the top side of the tunnel is very small.The lava tunnel is at a ten-minute walking distance to the south of Madelena. A sign post near Criacao Vella directs to the Grutas Das Torres. The cave has two entrances. The first entrance is open to the sky or a day lighted roof at one end of the tunnel. The other entry is a tunnel cavern opening which is inferred to have been formed due a slump in the roof. The tunnel has clear pahoehoe lava in some reaches while in some other reaches the roof has collapsed with large lava blocking the tunnel route making access hazardous and narrow. Lava gutters are also seen. A number of secondary tunnels also have impressive geological formations. The lava tubes have picturesque formations of stalactites (lavacicle
Lavacicle
Lavacicles are geological formations resembling small round-tipped stalactites that are found in lava tubes, the name comes from their resemblance to icicles....
s), stalagmites, lava
Lava
Lava refers both to molten rock expelled by a volcano during an eruption and the resulting rock after solidification and cooling. This molten rock is formed in the interior of some planets, including Earth, and some of their satellites. When first erupted from a volcanic vent, lava is a liquid at...
, lava bench
Lava bench
A lava bench is a volcanic landform with a horizontal surface raised above the level of the surrounding area. They are created when molten lava travels away from a volcanic vent and expands an old shoreline. If a newly formed lava bench rests on sediments, it may pose hazards due to its extremely...
es and side balls or balls of lava. Considering the large size of the cave, with further scientific studies more faunal species may be discovered.
The liquid lava that dripped from the roof of Gruta das Torres has formed into picturesque stalactite and stalagmite and also in several other formations and shapes. Inside the tunnel, it is humid as water drips from the roof and a constant temperature of 16 °C (60.8 °F) is recorded throughout the year. However, the entrance has a slightly higher temperature. The total drop is approximately 200 m (656.2 ft).
The tunnels formed within a pahoehoe type lava flow. The top of the flow cooled against the air and formed a solid crust, while beneath it the liquid lava continued to move. As the amount of liquid lava passing through them decreased, the tunnels emptied. Silica oxide is also seen in walls of the cave in some stretches of the cave. At the main entrance, after passing through the ‘Algar da Ponte’ ("Algar Bridge"), there is an avenue of trees. Some forms of plant life like ferns, mosses and lichens are also noted at the portal, floor and walls of the cave opening.
Deep inside, in the darker regions of the cave, mold
Mold
Molds are fungi that grow in the form of multicellular filaments called hyphae. Molds are not considered to be microbes but microscopic fungi that grow as single cells called yeasts...
, bacteria
Bacteria
Bacteria are a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals...
and insects have been identified. The troglobite
Troglobite
Troglobites are small cave-dwelling animals that have adapted to their dark surroundings. Troglobite species include spiders, insects, fish and others. They live permanently underground and cannot survive outside the cave environment. Troglobite adaptations and characteristics include a heightened...
faunal species found, typical of such caves, are the endemic species of Trechus Pico Machado and Cixius azopicavuz Hoch.
UNESCO Heritage List
Considering the large number of caves found in the Azores archipelago – 271 caves under four categories of Rank A, B, C and D, the Government of Azores has initiated a proposal for submission of a few selected caves to UNESCOUNESCO
The United Nations Educational, Scientific and Cultural Organization is a specialized agency of the United Nations...
for inscribing under the UNESCO World Heritage List. A Working Group on Volcanic Caves of Azores supported by the Azorean Speleological Inventory and Classifying System database has identified 30 Volcanic Caves of Rank A, which are located in the Graciosa
Graciosa
Graciosa Island is referred to as the White Island, the northernmost of the Central Group of islands in the Azores. The ovular Portuguese island has an area of 60.65 km², a length of 10 km and a width of 7 km...
, Pico
Pico
Pico- is a prefix in the metric system denoting a factor of 10−12 or .Derived from the Italian piccolo, meaning small, this was one of the original 12 prefixes defined in 1960 when the International System of Units was established....
, São Jorge, São Miguel
São Miguel
-Brazil:* São Miguel, Brazil, Rio Grande do Norte* Barra de São Miguel, Alagoas, a municipality in the State of Alagoas* Barra de São Miguel, Paraíba, a municipality in the State of Paraíba* São Miguel do Aleixo, a municipality in the State of Sergipe...
and Terceira islands for inclusion in the UNESCO List. Of these 30 volcanoes identified for UNESCO recognition, Pico island has the maximum number of 17 volcanic caves in the proposal, which includes the Gruta das Torres cave. The selection criteria for inclusion of the caves in the list was based on the scientific value, tourism prospects, approach conditions, perceived threats, data base and conservation standing.
Tourism
The first 450 metres (1,476.4 ft) are accessible to visitors accompanied by a guide. A visitor center built in basalt rocks and aesthetically merging with the environment, provides a guided access into the cave. The Gruta das Torres has been open to the public since 2005. Visitors are allowed in groups of 15 at a time and each visitor is provided with a protective gear of a helmet fitted with lamps to see the dark interior. At the visitor center, audiovisual presentations in EnglishEnglish language
English is a West Germanic language that arose in the Anglo-Saxon kingdoms of England and spread into what was to become south-east Scotland under the influence of the Anglian medieval kingdom of Northumbria...
and Portuguese
Portuguese language
Portuguese is a Romance language that arose in the medieval Kingdom of Galicia, nowadays Galicia and Northern Portugal. The southern part of the Kingdom of Galicia became independent as the County of Portugal in 1095...
give details about the cave. As of 2011, the tours are scheduled for 10:30, 12:00, 13:30, 15:00 and 16:30 for the months of higher visitation (15th June to 15th September).
The Visitors' Support Centre at the entrance to the cave has innovative architectural features – “a circular sweep and a linear spatial organization – a sequence of programmatic spaces that prepare visitors for the spectacle below.” It was awarded the "European Union Prize for Contemporary Architecture Mies van der Rohe Award 2007", in Barcelona
Barcelona
Barcelona is the second largest city in Spain after Madrid, and the capital of Catalonia, with a population of 1,621,537 within its administrative limits on a land area of...
. It was a formal award presented by the European Union
European Union
The European Union is an economic and political union of 27 independent member states which are located primarily in Europe. The EU traces its origins from the European Coal and Steel Community and the European Economic Community , formed by six countries in 1958...
, in association with the Mies van der Rohe Foundation.
The innovative construction of the visitor center ensures that the cave entrance has full exposure to the skylight. To achieve this, the layout has incorporated techniques of local building architecture in the form of 'currais de figueira' meaning 'fig tree walls” structure. Such walls used to be part of the vineyards in the region as protection from wind and seawater. This front elevation forms the natural southern part of the building. The wall which is 1.8 metres (5.9 ft) in height has an “open-weave structure” or undulating structure to permit natural lighting to the entire building, thus eliminating provision of windows. It also provides protection to the entrance into the tunnel. The building also incorporates a design which provides uniform illumination of the interior. It eliminates the need for other openings. Except for the wall at the entrance, the main building is painted with a waterproof black colour finish to match with the colour and texture of the vitrified lava inside the cave.