OverviewTrailhead: dam of La Sarra (1438m).
Time to summit: 5h-5h30min.
Because the long route is a good option the camping with the tent in the nice place of Lagos de Arriel, but the full route in the day is possible (5+4 hours, total 9 hours).
Note about GPX file: it was an ascent across Geodesics descending Ledormeur
Getting ThereSee the main page to approach to trailhead of La Sarra.
a) From Respomuso (2130m) go to the west following the mark of GR bordering the dam. After the dam the way go in the top part of the ravine of river Aguas Limpias and for a path in the hillside we reach the first lake of Arriel.
b) From La Sarra an important turn aside to whom there will be necessary to be very attentive in that a plate in the wall will indicate towards the rigth side ibones de Arriel (left side 1h). The way is easy initially for a nice forest but soon we will appear in a channel of stones with hard slope, it is barranco de Arriel (Arriel's ravine). We will follow the cairns (and marks of red paint) and in the middle part we will see the marks that take to us towards the right (east) for a narrow path in the hillside. Important: you must be carefull for take the route of red marks out of the path in the middle of ravine (if you go seeing the path in the ground you don't look the desviation and you must turn back from the top of the ravine).
We will come this way to the Arriel's first lake at 2170m.
After leaving the second lake to the right we will avoid the climb towards Arriel's top lake. You must to follow the path what it border the lake for below and the right. After the final of the lake we will leave towards the right the corridor (cairns) of route to Balaitous. The route is evident in direction to Col of Lavedan (N-NW) with a hard slope in the hillside with a lot of stones. Near of the col of Puerto de Lavedan at 2560m we leave the route in direction to the bottom of the south wall of Pallas.
In this point we search the key of the route the chimney of Ledormeur. The easiest chimney is the most nearest at the wall (right) with the begin in great stones of I+. The narrow channel begin in left direction with good rock (II-, 15-20 meters). The channel is wide now with free stones (I+ and I). The exit is a terrace in left at 2795m. We follow the path near of the ridge in N-NW to reach the channel over the NW face with some stepcrossings of I in right direction (exposed) and finally in the upper side over the great blocks of stones we reach the summit of Pallas (2974m).
c) From Arremoulit: generally the people of the refuge we climbed across the geodesic ridge with descent across Ledourmeur but the route is a good option as well. We follow the cairns to the Col of Pallas from the refuge (wide col evident under the Pitón von Martin) and descend to take the path with bring from the second lake of Arriel in direction to Port du Lavedan. From there is the same route to chimney.
Essential Gear-Summer: Helmet (fall of stones with people in chimney Ledormeur). Rope? (you had an anchorage in the first 35 meters of chimney). In summer and good weather conditions is not necessary generally but with people with less experience it's a good idea specially in the descent (of course you'll need a first person to climb to the anchorage without rope).
-Early in the season (may-june): With snow the chimney is a coulouir of 60º and the use of crampons and ice-axe is advisable. The upper terraces are exposed with snow in 30-40º.