97outside, as suggested by the famous author whom I have just
quoted.
Lacoste rallied behind the hypothesis submitted by
Montlosier but he did not offer any explanation nor addi-
tional argument (Lacoste 1805 ).
Particular mention must be made to illustrations painted
by the artist named Delécluze, who was accompanied to the
fi eld by a local guide recommended by the clergyman
Lacoste (Fig. 5.3 ). His watercolours, which aimed to be as
faithful as possible to the landscape, were certainly inspired
by what the geologists were able to observe on site at that
time. The chronicles also reported the constant presence of
knowledgeable local guides who used to lead the foreign
visitors to the interesting sites (Taylor 2007 ). These guides
were certainly the source of ideas that spread from one visi-
tor to another. In this context, Delécluze’s notes that comple-
ment his drawings can be read like the transcription of
comments obtained from his guide. In this context, his fol-
lowing remark is surprising on behalf of a non geologist: “ Ce
lac a du rapport avec plusieurs de ceux qui se trouvent dans
le Royaume des Naples. Dolomieu donne la Description de
celui qui est sur une des montagnes de l’Ile Pentellaria :
l’analogie est frappante (Voyage aux Iles Lipari, page 144) /
This lake has relationships with several lakes located in the
Kingdom of Naples. Dolomieu provides the description of
that lake which is located on one of the mountains of the
Pentellaria Island: the analogy is striking (Voyage to the
Lipari Islands, page 144) ” (Delécluze 1821 , comment on
watercolour board 36). In fact, this remark is better explained
if it had been prompted to him by an expert.
The fi rst author who published detailed observations
included in a work of great fame is George Poulett Scrope
( 1827 , 2nd edition in 1858). Regarding the lake Pavin, he
likely accepted the hypothesis provided by Montlosier with-
out any further questioning:
“ One remarkable and peculiar circumstance attends these cones
[ Mont Sineire and Montchal ] ; viz. the existence of a deep, large,
and nearly circular hollow immediately at the foot of each. The
bottom is covered with water, and they bear the names of the
Lakes Pavin and Mont Sineire; both are bordered by nearly per-
pendicular rocks of ancient basaIt. Their position announces
them to be contemporary with the eruption of the neighbouring
cones; and it seems probable that, like the Gour de Tazana
already described amongst the Monts Dome, they owe their for-
mation to a series of extremely rapid and violent explosions. ”
Poulett Scrope ( 1827 , 2nd edt 1858, p 118).However, and this was written explicitly for the fi rst time,
he proposed a chronological relationship with the neighbour-
ing strombolian cone of Montchal: both volcanoes would be
contemporary. But Scrope also referred to his description of
the Gour de Tazenat that he considered as an analogue:
“ [...] is a circular lake, called the Gour de Tazana, about half a
mile in diameter, and from 30 to 40 feet deep. Its margin for a
fourth of the circumference is fl at, and elevated above the valleyinto which the lake discharges itself. Every where else it is envi-
roned by steep granitic rocks, thickly sprinkled with small scoriæ
and puzzolana, and rising about 200 feet from the level of water.
These fragments are all that indicate the volcanic origin of this
gulf-like basin, but these are suffi ciently decisive. No stream of
lava or even fragments of any large size are perceivable.
This curious and, in Auvergne, rare variety of crater is iden-
tical in characters with some of the largest and most remarkable
of the volcanic maars in the Eiffel (particularly that of Meerfeld);
wilh this only difference, that the former has been drilled by the
volcanic explosions through granite, the latter through a superfi -
cies at least, of grauwacke slate and secondary sandstones.”
Poulett Scrope ( 1827 , 2d edt 1858, p 74–75).
The author acknowledged the presence of a deposit of
scoriae and pozzolanas scattered on the the surrounding gra-
nitic basement. Although he also mentioned the absence of
lava fl ow, he considered that the scattered volcanic materials
were enough evidence in favour of the volcanic origin of the
lake. He strengthened his diagnosis by using a comparison
with the maars of Eifel (in Germany). Subsequently, the link
with Lake Pavin remained established only on their morpho-
logical similarity. Unfortunately, and not better than
Montlosier , he did not recognize the deposits resulting from
the eruption of Pavin as he was looking for scorias and poz-
zolanas only.
The following geologist who became interested in the
lake Pavin is Jean-Jacques Nicolas Huot who drafted the
article “ Volcanoes ” in Nicolas Desmaret’s posthumous ency-
clopedia in 1828. From an updated extract of the map of N.
Desmarest published in 1827, he proposed a very surprising
explanation: lava fl ows, which were produced by the puy de
Montchal, would have by-passed an unknown obstacle,
which later disappeared, and the lake would then have taken
the place of this obstacle:
“ Le lac Pavin produit une illusion complète au premier abord
(see board 44 [Fig. 5.4 ]) ; sa forme circulaire, ses contours
élevés, formés de laves & disposés en entonnoir, donnent tout-à-
fait l’idée d’un ancien cratère; mais l’ouverture par laquelle
s’échappe au nord la petite rivière de la Couse, les pentes, par
lesquelles se terminent les deux extrémités, de sa masse volca-
nique circulaire, de chaque côté de l’ouverture, n’offrent point
les traces d’une rupture opérée par la lave, puisque le cours de
la rivière n’est à la sortie de ce lac encombré par aucun reste de
coulées. D’ailleurs le diamètre des parois du lac Pavin ne seroit
point en rapport avec leur élévation absolue au-dessus du sol. II
faut donc, pour expliquer la formation de ces parois, admettre,
comme l’inspection des lieux semble le prouver qu’un courant
de lave sorti du puy de Monchal, beaucoup plus élevé que les
laves du lac, s’est partagé en deux branches circulaires qui se
sont terminées à l’endroit même d’où sort la petite rivière : un
effet aussi singulier dans la marche d’une lave en fusion a
quelque chose qui doit surprendre, mais sans doute un obstacle
aujourd’hui invisible a déterminé la coulée à se partager ainsi.
Quant à la profondeur du lac lui même, abstraction faite de la
hauteur des parois, on peut l’expliquer en disant que la coulée
qui les a formées s’est déposée sur un sol qui forme encore le
fond du lac, dont la profondeur est cependant de 120 pieds; les
laves se seront répandues tout autour en exhaussant le sol
jusqu’à une assez grande distance. La petite rivière coule à la5 The Origin of Lake Pavin: Two Centuries of Controversy