The times. [volume] (Richmond, Va.) 1890-1903, 1892-06-19

when breakage Of a portion OF the sur
! fare takes place along the weakest portion
thereof. Every miner is familiar with the
"fauitsr which he encounters IN the line
Of his drifts, and rarely can he tell whether
the continuation Of his vein Is above or be
Low him when he comes TO a bare wall at
the abrupt end of bis vein. 1t is well
known to geoIogists that the faults are OF
ertraordinary depths, rs shown in the
region cut through by the canyon Of the
Colorado.
The phenomena attending these great
descriptions are weakly exhibited in the
eartaouakes of today, when small disloca-
tious occasion comparatively great results.
In the great earthquakes in Japan, nota-
bIv in that of 1854, and In great earth
ouakes along the Andean coast Of South
America. there have been relatively small
changes of surface that have exhibited
but little change of the surface of the
earth. Nor has there been any exhibition
NJ forces in these earthquakes that cannot
be explained on the theory of the rupture
IF a relatively very small area OF the earth's
surface.
In the great earthquake of Krakatoa,
few years since, there was an unusual ex-
hibition Of explosive forces accompanying
the disruption of the surface, when vol
canic agencies blew up half Of high
rocky islet and left great depression be-
low the surface of the water. There has
been no such other exhibition in modern
times, for the material of the islet and the
submarine material was projected into
the higher atmosphere in very minute
particles, and gave rise to the extraOrdi-
nary exhibition Of the beautiful red skies
visible near sunset This matter was car
ried around the whole earth in the higher
atmosphere.
The mechanical theory of heat will read
fly explain how great disruption of the
earth's surface may produce all the phe-
nomena of volcanic action when the condi-
tiOns OF the material and the extent Of the
rupture are invariable. Imagine what
must have been the intensity Of heat de-
veloped when faults of one mile deep were
formed, and the terrible friction of two
surfaces Of such great extent were in
volved. We can only approach the sub
ject by the mathematics Of the theory Of
heat, and certainly not by any experience.
Along this coast the lines of rupture Of
the weak parts of the earth's crust are
shown in the depression of the plateau OF
the Pacific ocean bed and the parallelism
of at least four lines Of coast mountains
and the great backbone of the Sierra Ne
vada and Cascade range. And these lines
and the closely adjacent country must be
the seat Of seismic changes, as the earth
gradually loses its heat. We have the
evidence clearly before US that along the
line of rupture of these ranges there have
been many overflows Of lava forming the
basaltic layers visible in the Sierra Nevada
in certain localities. and especially in the
many overaows along the northern part Of
the Cascade range.
The dynanical theory accounts for these
resultant exhibitions, and il is easy to
imagine that there must have been many
other concoInitant exhibitions of electrical
and volcanic forces. In the great chain Of
the Aleutian islands, where so many ex-
tinct and active volcanoes exist, every
earthquake along this weak line in the
earth's surface is accompanied by renewed
activity in the living volcanoes, and it may
be safely assumed that all the phenomena
may be traced to the contraction and rup-
ture of some part Of the surface or crust
from the ceaseless but slow cooling of our
planet.-Professor George Davidson in san
Francisco Examiner.