Changes in the Pyrenean peaks

Topographical measurements of Sostremetries alter the list of three thousands: the lower Gias enters as a three thousand and the western Clarabide ceases to be a three thousand.

A group of five Catalan topographers, known as Sostremetries, have confirmed a new three-thousand-metre peak in the Pyrenees. This is the Gías Inferior, in the Estós Valley, in the Aragonese Pyrenees, which exceeds three thousand metres by 59 centimetres. Until now, no official cartography had given it an altitude of more than 3000 m and it was not even considered a summit because its prominence had not been calculated with sufficient precision. With the validation of these two basic criteria, the Pyrenees now have a new peak that exceeds 3,000 metres.

The members of the Sostremetries expedition to the Gías Inferior left the Estós Valley on Thursday 21 September and spent the night at the Estós refuge. The following day, the surveyors climbed the col and the summit of Gías Inferior to measure them accurately. The first real time measurements in the Estós Valley already indicated that it could exceed three thousand metres by very little. The measurements at the col also showed a prominence clearly higher than 10 metres. Finally, back in the office, the results of the post-processing calculations confirmed it: the lower Gías is the new summit of the Pyrenees, with an altitude of 3,000.59 m and a prominence of 13.47 m.

Background

In December 1995, the International Union of Mountaineering Associations (UIAA) published the first official list of the 212 summits over 3,000 metres in the Pyrenees in its bulletin No. 152. To appear on the UIAA list, four requirements had to be met: the peak had to be at an altitude of 3,000 m or more, have a minimum prominence of 10 m, have a name and appear on a map or in a guidebook. The latest technological advances in the generation of cartography made it possible to dispense with the last two requirements, which are now ephemeral and do not respond to any technical need. Fourteen years later, the group of mountaineers known as the Ghostbusters was born and began to revise the UIAA list using GPS hiking receivers and considering the only two technically essential rules, altitude and prominence. These devices are accurate to within 3 metres at best, but this has already allowed them to resolve some of the most glaring inconsistencies in the UIAA list.

This is where Sostremetries comes in. Most of the mountains in the Pyrenees had never been measured directly on the ground or had never been measured with centimetric precision. Armed with professional surveying instruments, the group of engineers has the ability to resolve the most difficult uncertainties and certify the altitude of all the peaks they measure.

Sostremetries 2023 Campaign

This year, the team received technical support from Leica Geosystems, which provided them with state-of-the-art surveying instruments and calculation software.

In this year's campaign, from June to September, the Sostremetries team measured eight peaks in the Catalan and Aragonese Pyrenees that were just on the threshold of the symbolic three-thousand-metre barrier. As a result of the calculations, there have been several changes in the list. While the Lower Gías now crosses the 3,000-metre barrier with sufficient prominence, the western Clarabide is now just a ridge. In this second case, although it measures 3,007.44 m, it cannot be considered a summit as it only has 9.12 m of prominence. The rest of the measurements of the campaign give the following altitudes: Salenques is 2,994.81 m; Frondella SW, 2,999.00 m; Punta de Passet, 2,998.49 m; Pico Pequeño del Portillón, 2,998.66 m; Piedras Albas, 2,997.63 m; Pico de Cregüeña, 2,994.21 m.

Upcoming events

• The 10 NovemberSostremetries will present the results of the expedition to the Gias Oriental at the Mountain Book Fair held in Vic.

• The 25 October will hold a talk at the EPSEB Escoal Politècnica Superior d'Edificació de Barcelona de la UPC Universitat Politècnica de Catalunya. More information here (link).

This group of mountain lovers was created in October 2020 to disseminate the use and service of topography. Andreu Alvarruiz [ICGC (Institut Cartogràfic i Geològic de Catalunya)], Oriol Boixareu (GeoLímits), Marc Calaff (Geolegnia), Salvador Sala (Montgraf, Monteditorial and Montquercus) and David Segura (Generalitat de Catalunya) are part of it. These five Catalan topographers are already planning new expeditions, they will not forget the Pyrenees, although they do not rule out some incursion further afield.