586 
PROFESSOR FORBES ON THE TEMPERATURES 
considered to be highly medicinal. Its temperature must exceed by a few degrees 
the mean temperature of the place. 
C. Temperature of the Springs . — 1835, July 11. Elevation estimated from barometri- 
cal observations, 2558 feet above the sea : 
Crichton. Reduced. 
° ° 
Source Vieille (from repeated observations) . . 93’2 9T4 
Source Froide, ou de la Montagne 55‘2 54 4 
The valley of Ossau and that of the Eaux Bonnes have a very damp climate, being 
situated near the first lofty summits which meet the warm westerly winds, and con- 
dense their moisture. Being almost completely insulated, these valleys are seldom 
visited except by invalids. The traveller on foot, however, need not return to Pau 
to resume his journey, but may cross the Col de Tortue, (clay slate,) at a height of 
5970 feet, (by my observations,) and descend upon the charming valley of Azun, and 
the yet richer environs of Argellez. From thence by Pierrefitte he may arrive at 
Cauteretz, which is the next thermal establishment in the order we have adopted. 
III. Cauteretz. 
A. Geological Position . — The Valley of Cauteretz, like most of those of the Pyre- 
nees, is transverse to the axis of the chain. From the opening into the valley of 
Bareges, or Lavedan, at Pierrefitte, (between Argellez and Luz,) it consists chiefly 
of clay slate, intersected by some veins of quartzose porphyry and beds of limestone. 
These strata are highly inclined, and at Cauteretz are nearly in a vertical position. 
They at the same spot undergo a very remarkable alteration, becoming much harder 
and heavier, and altogether assuming, for some distance, a character analogous to the 
very remarkable “ Bareges formation,” of which I shall presently have to speak, the 
rocks of which are generally referrible to the hornblende family. I impute this 
change to the neighbourhood of the granite, which rises in vast masses to the south- 
ward, forming part of the great central mass extending to the Vignemale, and in 
which lies the upper part of the Valley of Cauteretz and that of Lutour, which, for 
romantic interest, equal almost any in the Pyrenees, and strikingly resemble the pine- 
clad ravines of the higher Alps. Nothing can be more striking than the reference 
which the positions of the hot springs bear to these geological features. The actual 
junction of the granite and slate is beautifully seen by the side of the road, just be- 
fore crossing the bridge of La Railli&re, above Cauteretz. This junction likewise 
separates two very distinct groups of hot springs ; the one group rising in the slate 
formation in and behind the town of Cauteretz, the other issuing immediately from 
the granite further up the valley (commencing at about three quarters of a mile from 
the town, and occurring at intervals as we ascend towards the Pont d’Espagne). 
