ICE TSUNAMI IN THE ALPS - Tambora: The Eruption that Changed the World - page 91

The provincial government had sent Venetz—a true montagnard—to deal with the crisis. In
return, the valley residents offered Venetz their most knowledgeable guide, a chamois hunter
from the town of Lourtier named Jean-Pierre Perraudin, to accompany him on his tour of the
site of potential cataclysm.
Figure 7.3. Map showing the concentration of glaciers around Mauvoisin. The mountainous borders of
the Val de Bagnes created a funnel for the pent-up waters of the Dranse in 1818, with the market town of
Martigny in its direct path. (Jean Grove, The Little Ice Age [London: Methuen, 1988], 174.)
Perraudin is a remarkable figure in the history of nineteenth-century science. 16 With little
education and no academic credentials whatever, he nevertheless took it upon himself to con-
vert any science-minded individual who crossed his path to the long-held local belief that the
Val de Bagnes had once been covered in a vast sea of ice. For evidence of this, he pointed to
the existence of striated marks on rocks high above water level; to the presence of moraines
that seemed to mark the outlines of an enormous ancient snake of ice now vanished; and to
the anomalous, high-up location of giant boulders, called “erratics,” whose mineral constitu-
tion did not match that of the rock formations around them.
Joining Venetz and Perraudin on their urgent trek to the Giétro glacier was the director
of the nearby salt mines at Bex, Jean de Charpentier, a respected naturalist whom Perraudin
had already attempted to convert to his glacial theories, without success. 17 Charpentier later
recalled their geological conversations, in which he had found himself persuaded that the
prevailing view of the transport of enormous boulders by water, especially uphill, was indeed
an impossibility. Nevertheless, Perraudin's larger idea that the entire Rhône Valley had once
been submerged beneath a sheet of ice hundreds of feet thick struck him as pure hogwash, a
fantasy “so extravagant that I considered it not worth examining or even considering.” 18
Charpentier's reaction was typical of nineteenth-century geologists when first introduced
to glacial theory: amused disbelief. The emerging scientific communities of Europe prided
themselves on their intellectual sobriety—their quasi-sacred commitment to observed phe-
nomena and empirically testable facts. To succumb to fantasies of an icebound planet—a
world so utterly different from the visible one—spoke of medieval-style madness, a nonsense
superstition. In key individual cases, however—including Venetz, Charpentier, and later
Charpentier's student Louis Agassiz—this initial outright rejection of glacial theory was fol-
lowed by a period of increasingly serious reflection on the evidence in its favor, culminating
in a conversion to the glacialist cause almost religious in its intensity.
One imagines Perraudin teasing Venetz's curiosity with the heretical image of vast Alpine
ice sheets as they clambered up Mount Le Pleureur toward the Giétro glacier in the spring of
1818. Perhaps Perraudin knew that Venetz, in addition to his day job as engineer of Valais,