Mineral Point tribune. (Mineral Point, Wis.) 1869-1938, 1885-03-05
THE EARTHQUAKES IN SPAIN.
According 10 an Eminent Spanish
GeoIogist, the IiberIan Peninsula
Is Badly Cracked

Society Of Natural History the dis
tinguished Spanish gcologist. Don
Macpherson, read a paper on the
earthquakes that have caused, this
winter, so much destruction in the
province of Andalusia. If Senior
Mcpherson IS not mistaken, the Span
/ ish peninsula was cracked at remote
epoch; the crack extended clear
through, and the two parts have not
been properly cemented at the adiOin-
ing edges. The crack appears to
have extened from the Bay of Biscay,
near Cape Ortegal, in an indirect line
to the Mediterranean, cast of Malaga,
dividing the peninsula into two foes
| (as an Arctic marine might remark,
the edges Of which have a tendency
to sink under the accumulating weight
of tertiary deposits. The Andalusian
district, where the oscillations have
been most violent, seems to be situat-
ed directly over the crack at the
point Of least adhesion between the
1 two Hoes . The Times gives a
| translation of the remarks of Senior
Macpherson from The Madrid Globe.
The earthquake that took place in
the peninsula on the night of Dec %,
and has not even yet terminated has
taken a character of such interest and
presented IN It's manifestations of such
marked relation to the geological
structure of this part of the earth,
that | consider it of interest to enter
into some details respecting the most
important features of this phenome-
non.
In relation to the whole peninsula,
the earthquake divides itself in three
successive phases-one of little rela-
tive importance that took place on
the morning of Dee. %, and was linn
tied to the western part of the cOun-
try, GalIcia and Portugal only having
participated in its effects; another, of
very great Importance, three days
afterward, or at o'clock on the night
of Dec. 25 and the third, compre-
hending the oscillations that have
since occurred, and are even yet oc-
curing, in the district where the tenlb-
tor of December 20 was most destruc-
tive.
This chief oscillation covered an
extensive region. An appreciable
movement of the earth appears to have
extended through all the space be-
tween Cadiz and Cape Gaia, from
Malaga to the Cordillera Carpetena.
The movement, according To all the
data now known, increased in inten-
sity from this mountain range toward
the south, and reached its maximum
in the region comprehended between
the Serrania de R0nda and the Sierra
Nevada.
In Madrid the trepidation was very
preceptible, sufficient to stop some
bells, the movement apparently being
pendular, and directed from north to
south.
There were noted two successive
oscillations, each of two or three sec
onds' duration, and separated by an
interval of three or four seconds.
| The movement, as | have said, was
| gradually accented in the direction of
south, and more especially after de-
parting from the southern border OF
the central table-land or northern de
markahon of the valley of tse Quad
alquivir.
Now, the point Of interest presented
by this phenomenon is in the coinci
dence that appears between its diverse
manifestations and the geological
structure Of the peninsula; and to
make this clear | may be permitted to
state some facts respecting the latter.
The primitive geological formation
of the peninsula presents, with rude
exceptions. a series of folds, trending
with singular consistency from south
west to northeast, a type of which
peculiarly is seen in the Cordillera.
| Carpentana, that traverses the PENN
sula in almost its whole extension.
! Subsequent to this folding, that hap
pened in an epoch anterior to the
paloeozoic, were deposited the cam
brian and sllurlan sedimentary rocks,
and these in their turn were also fold
ed, but from northwest to southeast,
or in a direction that to the anterior
folds, forms almost a right angle
| With this folding of the sedimentary
strata comedies the appearance of a
broad zone, that traverses the PENN
sula from Galicia to the valley of the
Guadalquivir, of great masses of
granite, porphyrite, and other print
tive rocks, that to day, geologically
speaking, segments the peninsula in
two distinct portions.
The great band, that appears is one
of the most remarkable geologic ac-
cidents of the peninsula, cuts and
segments the archaic deposits Cam
brain. etc. in a manner truely nota-
BILE, as can be seen in the great rents,
even in the central Cordillera Car
petana, in the interruption it suffers
between the Sierra lie Gaia and the
Sierra de Estrella, in Portugal
Studying the Mediterranean slope
OF Andalusia, there will be seen two
great masses, principally of primary
formation, one of them called the
Serrania de Ronda and the other the
Sierra Nevada. both produced by
series of folds and fractures with a
course from southwest to northeast,
and having between them a space
filed by the latter deposits About
midway OF this space like an island
in the midst # these more recent de-
.posts. appears a series of SUBMITS.