Autor(es):
Sá, Artur Abreu 
; Gutiérrez-Marco, Juan Carlos ; Meireles, Carlos
Data: 2008
Identificador Persistente: http://hdl.handle.net/10400.9/374
Origem: Repositório do LNEG
Assunto(s): Património geológico; Património paleontológico; Parque Natural de Montesinho (Portugal)
Descrição
Deep in the memory of the inhabitants of the region of Montesinho (NE Portugal), there is a legend
which talks about the existence of enigmatic pedras escrevidas (="written stones") in the mountains
near the village of Guadramil. In the first half of the 20th Century, what used to be considered some
kind of rock engravings in quartzite, were studied by archaeologists, which interpreted these signs as
a kind of very old (and unknown) pre-Roman writing. A modern geological mapping of the area of the
Montesinho Natural Park allowed us to rediscover the original sites of these structures and interpret
them as ichnofossils. They occur on the Lower Ordovician quartzites, towards the top of the lower
member of the Marao Formation (Floian), which crops out extensively in the area, generating the
mountainous relief of the Barreiras Brancas-La Culebra sierra. The study of the locality required two
excavating campaigns, supported by the Portuguese Ministry of Science, which involved 40 highschool
students during the summer of 2002 and 2003 in an area located 5 km north of Guadramil and
very close to the Spanish border. It resulted in the exposure and cleaning of an exceptional surface of
40 square meters with a very vast ichnofossil accumulation, reaching a maximum of 2,000 individual
specimens by square metre. All of them correspond to horizontal sections of conical structures created
by the spiral displacement of steeply inclined J-shaped burrows, assigned to the arthrophycid forms
Daedalus halli (Rouault) and Daedalus labechei (Rouault). Both ichnotaxa are widely known in the
"Armorican Quartzite" facies of the Lower Ordovician of SW Europe, where massive occurrences reflect opportunistic colonization events on storm generated sandstones. The spectacular bedding plane
concentration of these conical burrows in the locality, and the good preservation of the active backfill
on their typical spreite (wing-like) structure, is currently being mapped with the purpose of
determining the mathematical model underlying the burrowing pattern and ecospace interaction
between the sedimentivorous producers. Anyway, this outstanding palaeontological site of the "pedras
escrevidas" has no other counterpart in the world, and is of undisputable value for the Iberian
geological heritage. In the near future the locality will be protected and included in the touristic
programmes and guides enhancing the natural heritage of the Montesinho Natural Park. The detailed
ichnological study of this outcrop is being financed through the PATRIORSI project of the Spanish
Ministry of Education and Science (CGL2006-07628/BTE, years 2006-2009) and by the project
"Identification, Characterization and Conservation of Geological Heritage: a Geoconservation strategy
for Portugal", sponsored by the Portuguese Foundation of Science and Technology (PTDC/CTEGEX/
64966/2006, years 2006-2009).
