Tresviso 2019

Andara (Eastern Massif) viewed from Tresadura (looking South) (Phil Walker)

The 2019 expedition is only 5 weeks away. Hopefully some interesting blog posts will be created, but firstly, as per previous years, a bit of a brief overview of expedition:

Overview & brief history:
The Picos de Europa is a range of mountains 20km inland from the northern coast of Spain, forming a westerly extension of the Cantabrian Mountains. It consists of three main areas, the Western, Central and Eastern Massifs.

  • The Western Massif is to the west of the Rio Cares and has been explored by a selection of clubs including Oxford University Caving Club (OUCC), Seccion de Espeleologia Ingenieros Industriales (SEII), York University Cave and Pothole Club (YUCPC), Sociedad de Espeleologia Geologicas (SEG) and Speleo Club de Paris (SCP). This now includes the area under exploration as part of the Ario Caves Project.
  • The Central Massif is between the Cares Gorge and the Rio Duje and has been mainly explored by the Speleo Club de Seine (SCS).
  • The Eastern Massif is to the East of the Rio Duje. Lancaster University Speleological Society (LUSS) were exploring the Eastern Massif from the early seventies to 1987 with the help of SEII.

It was the Eastern Massif (or Andara) that drew the attention of LUSS in the early 1970s. In the early years exploration was mounted from the mountain village of Tresviso and exploration was dominated by the resurgence cave Cueva del Nacimiento (Cueva del Agua) located at the foot of the mountain range. The resurgence flows into a canal that contours the Urdon gorge with an average flow of 2 m3/s and the cave behind the resurgence leads to >12 km of surveyed passage and a height gain of over +534m.

The catchment is some 40 km3 and includes caves such as Torca Jou Sin Tierre (CS-9) at -1203m deep and Torca del Cueto de Los Senderos (Sima 56) at -1169m deep.

Morning Chamber, Cueva de La Marniosa (Joe Daniels)


In the late 70’s LUSS pushed Cueva del Nacimiento to around the 11km and +300m mark, but after several years the cave was abandoned as all the major routes sumped and no continuation could be found. LUSS then turned their attention to the Andara region higher up the mountain range and sought caves that would drop into the Nacimiento system and hopefully create a record-breaking >1500m traverse. They found a number of deep caves around this ‘top camp’ area; Sara, Tere, Flowerpot, Dosser’s Delight and Sima 56 were all pushed to respectable depths but a
connection remained elusive.


The discovery of newer and deeper systems, plus improved GPS, have changed the figures slightly but a connection between the deep potholes and resurgence would create; a cave in the top 10 worlds’ deepest, deepest in Spain and potentially one of the the deepest underground traverses in the world.

Top EntranceAreaAlt(m)Current Depth (m)Vertical Range (m)
S-33 Torca de la Hendida Samelar2100-4521620
CS-9 Torca Jou Sin Tierre Cueto Senderos 2074 -12031594
Sima 56 Cueto de Los Senderos Cueto Senderos 1975 -11691495
T82 Karen – 2.6 Sara Grajal (Sara depression) 1880 -5911400
T145 – Pozo Castillo Mazarassa 1870 -3091390
2.24 Tere Grajal (Sara depression) 1820-7921340
FT39 Compromisso Mazarassa 1820-3131340
T169 Flowerpot Pico Boro 1785-7231305
T173 Dossers Delight Pico Boro 1706-8311226
T190 Septrin Pico Boro 1696-1801216
3.2 Torca Branarredonda (Fallen Bear) Samelar 1589-4561109
T510 Cueva Entre Cuetos Sierra del a Corta 1305-117825
T69 – Pozo Motilla Sierra del a Corta 1248-70768

Table: Potential depth if connected to Cueva del Nacimiento (2017).

Note: There are at > 70 sites at higher altitude than CS-9 that would surpass -1600m deep through trip, with some close to -1800m depth.

Survex – Mountain range looking E-W

Expedition Dates
• 31 st August 2019 to 14th September 2019 – main expedition dates

Objectives
The expedition has several goals. The following are a few primary objectives:

Cueva del Nacimiento

  • Jurassic World – The Sandy dig, draughting lead, now only an hour from camp
  • Pina Colada Bypass – calcite aven to climb
  • Joe’s Crack – continuing shaft behind Death Race camp.
  • Teeth of Satan – Wet Aven – +30m aven with draft and calcite squeeze, requires enlarging.
  • Dan’s Big Room – unexplored section of maze in area of Dan’s Big Room, Peanut Chamber and Winter Gardens
  • Parting Friends – a dive of the Parting Friends sump is planned.
Pena Coloada Sump (CUeva del Nacmiento) (Rob MIddleton)

Cueva de la Marniosa

  • Beyond Sump 2 – undescended 6m pitch
  • T20A Silvestre – Marniosa – first through trip to be completed
  • T20A Silvestre – upstream leads, heading toward the Valdelafuente

Secondary Objectives:
Time and resources permitting there are several secondary objectives that will be attempted:

Downstream Marniosa (Joe Daniels)


Sistema Castillo
A large mine and natural cave complex in the Minas de Mazarrasa area. Pozo del Castillo series was explored to – 292m depth in 1983, with either a howling draft or roaring waterfall beyond a constriction at the limit. The potential of the cave is significant but currently a collapse prevents getting to the end. Pozo Natacha series ends at -309m depth and is close to the same point in Castillo.

  • Pozo Del Castillo – shoring and bypass of rock collapse Castillo remains a major lead, if we can get past the blockage! In 2018 the snow level had dropped and possible to get into the next section.
  • Pozo del Castillo – other entrances. FT16 entrance snow plug would appear to be the same blockage in lower Castillo passage. Snow plugs are reported further into the cave, so another entrance must exist!
  • Pozo del Castillo – surveying of Natacha upper series and locating possible surface entrance,


Valdelafuente / Sobra Valley

  • Re-locate draughting surface entrance on Valdelafuente, close to 80m aven beyond Sump 1 in Cueva del Marniosa,
  • Yorkshire Inlet in Cueva del Marniosa. Exploration of col above aven

Sierra del a Corta

Above the furthest reaches in Nacimiento is the Sierra del Corta. A heavily wooded area with a number of promising leads, that could potentially drop into Nacimiento and provide an easier route into the back-end to aid exploration at the far reaches.

  • T554 – large 100m shaft on the Sierra del a Corta, this requires some digging at the bottom,
  • Al2 – a drafting shaft not yet bottomed. Jurassic World in Nacimiento appears to be heading directly towards this site,
  • T294 Oh What Pot (La Gobia) – continuing passage,
  • Surface prospecting close to vicinity of Terror Firma in Nacimiento. Terror Firma is only 40m vertically and 200m horizontally from some parts of the surface in the Sierra del a Corta region.

Other

  • Locate and descend FT43, this draughts strongly. It is almost directly above Boulder Chamber in T87 Mazarrasa and would provide bypass to collapse at T87 entrance.
  • Prospecting on Hoyo Oscuro and Hoyo Evangalista. Highest entrances on the mountain range.
  • Mine 2.32a – there is large unexplored level (with tram lines) leading to unexplored passage.
M6 Toll Bypass, Cueva del Nacimiento (Arwel Roberts)