Vernon County censor. [volume] (Viroqua, Wis.) 1865-1955, 1906-10-10
BY THOMAS AUGUSTUS JAGGAR, Jr.
Assistant Professor of Geology, Harvard University.

I briefly as follows: In 1904 there was
lava flow which stopped in Septem-
Der of that year. In May, 1905, lava
flowed from split in the northwest
side of the cone and continued in
active motion throughout the year.
1t ceased flowing at the time when the
present eruption opened new vent
on the side of the cone. On April /,
1906, a splendid black "cauiiiiower"
cloud rose from the crater. On April
4, 5, and lava mouths opened
along the southern rift above men
toned. first 500 feet below the summit,
then 1900 feet lower, and finally 600
feet lower still, all in the same radial
line The lowest mouth was more
than half way down the mountain ana
from this orifce came the destructive
streams. 1t should be borne in mind
that these flows are not floods CT lava
which cover the whole slope Of the
mountain, but relatively narrow snake
like trickles, none the less deadly
when they push their way through
closely built town. The molten rock
crusted over and cracked, making
tumble of porous boulders at its front.
At D. m, April 7, column of dust
laden steam shot up four miles from
the crater vertically The cloud snap
ped with incessant lightnings. New
lava mouths opened and the flows
moved forward, crushing and Turning
and swallowing parts of Boscotrecase,
the stream forking so as to spare some
portions of the town. Meantime tor
rents Of ashes fell on Ottajano on the
opposite side of the volcano, and
many roofs collapsed and lives were
lost. At the observatory DR. Matteuci
and his colleagues were obliged to re-
treat, as the observatory was rocking
violently and heavy stones were fail
ing.
They went only half way down the
mountain, however, and returned tol
their posts next day The observatory
was uninjured, although stones had
fallen weighing as much as uye
pounds. The stones aud sand of the
eruption are mostly composed Of az
cient lavas broken up by the steam
blast. On April the electrical dust
cloud still hung over the volcano, but
thereafter through a fortnight the ex-
plosions diminished in violence until
only quiet steam rose. On the 18th
bad gases were blown downward on
the observatory by a strong southeast
wind, and some persons nearly lost
their lives by asphyxiation. The
gases were probably both carbon di-
oxide and sulphuretted hydrogen.
BUsotrecase was ruined wholly by J
laye, Cttoiano by falling gravel Bos-
cotrecase IS trayersed in two places by i
the clinlIery lava stream and in some |
cases houses were literally cut in two. |
The stream Of lava had forked about |
a spur Of the mountain. leaving the |
higher land with its vineyards I'M !
touched The lower land with RS
town was invaded There is so lit !
tie timber in the italian masonry. con
struction that the uninvaded part OF |
the town was not burned at all Att
Ottaiano the roofs fell in under the
weight Of sand and gravel The roofs
we're largely fat or slightly slopin :
tiled affairs The ash and lapiEi !
reached a depth Of three feet on level
surfaces. The roofs carried the walls
with them in many cases, but there
was no significant earthquake. There
was no fire, destructive lightning, nor
strong wind. The persons who per
ished were all found In the houses
where the sole cause Of death was en-.
tombment in the ruins.