W. L. (William Larkin) Webb.

Brief biography and popular account of the unparalleled discoveries of T.J.J. See .. online

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the forces converging at the smaller angle of 105, and therefore
compounding more effectively to produce a greater power of uplift,
for equal energy directed from the side of the sea.

And as the observed phenomena confirm the theory in every
detail, one finds it very difficult to believe that any other cause
has shaped these stupendous uplifts of the earth's crust.

It is also easy to see why the height of the plateau of Tibet
is less towards the east, where the elevation is only 11,000 feet.
For in the eastern part only a side pressure was available for the
uplift, and the forces of elevation did not converge towards a
point, as in western Tibet and near Lake Titicaca, in Bolivia.

5. Some phenomena connected with the great earthquake at
Arica, August 13, 1868.

One of the most important means of judging of earthquake
phenomena is the evidence afforded by eye-witnesses; and this
becomes especially valuable when we know the nature of earth-
quake processes, because it then becomes possible to see in the
descriptions given by eye-witnesses new meaning.

Accordingly, we add a brief account of the terrible earthquake
at Arica, August 13, 1868, which was a continuation of the move-


ments directly concerned with the uplift of the plateau of Titicaca.
For it was a survival of the ancient movements which brought
about this elevation, and as the region is still near the sea, it is of
special interest, because it bears on the elevation of the plateaus
of the Himalayas, now further inland.

In his "Light Science for Leisure Hours," p. 199, the late
Professor R. A. Proctor describes the havoc wrought by the earth-
quake at the neighboring town of Arequipa as follows:

"At five minutes past five (P.M.) an earthquake shock was
experienced, which, though severe, seems to have worked very
little mischief. Half a minute later, however, a terrible noise was
heard beneath the earth; a second shock more violent than the
first was felt; and then began a swaying motion, gradually in-
creasing in intensity. In the course of the first minute this
motion had become so violent that the inhabitants ran in terror
out of their houses into the streets and squares. In the next two
minutes the swaying movement had so increased that the more
lightly built houses were cast to the ground, and the flying people
could scarcely keep their feet. 'And now/ says Von Tschudi,
'there followed during two or three minutes a terrible scene. The
swaying motion which had hitherto prevailed changed into fierce
vertical upheaval. The subterranean roaring increased in the
most terrifying manner; then were heard the heart-piercing shrieks
of the wretched people, the bursting of walls, the crashing fall of
houses and churches, while over all rolled thick clouds of a yellow-
ish-black dust, which, had they been poured forth many minutes
longer, would have suffocated thousands.' Although the shocks
had lasted but a few minutes, the whole town was destroyed. Not
one building remained uninjured, and there were few which did
not lie in shapeless heaps of ruins."

This description was drawn for the phenomena observed at
Arequipa, but that it would serve equally well for Arica is suffi-
ciently indicated by the accompanying photographs of the town
as it was before and after the earthquake. A more terrible record
of desolation could hardly be imagined.


From photographs in the possession of Mrs. E. V. Cutts, of Mare Island, California.


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With this brief but striking description of the earthquake, we
may now turn to the seismic sea wave at Arica, and here I shall
again quote Proctor's account, which is based on the elaborate
technical memoir prepared by Professor F. Von Hochstetter in the
Sitzungsberichte of the Vienna Academy of Sciences for 1868, Vol.
LVIII, Abth. II. Proctor's account runs thus:

"At Arica the sea wave produced even more destructive
effects than had been caused by the earthquake. About twenty
minutes after the first earth-shock, (i.e. 5:25 P.M.) the sea was
seen to retire, as if about to leave the shores wholly dry; but
presently its waters returned with tremendous force. A mighty
wave, whose length seemed immeasurable, was seen advancing
like a dark wall upon the unfortunate town, a large part of which
was overwhelmed by it. Two ships, the Peruvian corvette ' Amer-
ica' and the United States 'double-ender' * Wateree,' were carried
nearly half a mile to the north of Arica, beyond the railroad which
runs to Tacna, and there left stranded high and dry. This enor-
mous wave was considered by the English vice-consul at Arica to
have been fully fifty feet in height.

"At Chala, three such waves swept in after the first shocks of
earthquake. They overflowed nearly the whole of the town, the
sea passing more than half a mile beyond its usual limits.

"At Islay and Iquique similar phenomena were manifested.
At the former town the sea flowed in no less than five times, and
each time with greater force. Afterwards the motion gradually
diminished, but even an hour and a half after the commencement
of this strange disturbance, the waves still ran forty feet above
the ordinary level. At Iquique, the people beheld the inrushing
wave whilst it was still a great way off. A dark blue mass of water,
some fifty feet in height, was seen sweeping in upon the town with
inconceivable rapidity. An island lying before the harbour was
completely submerged by the great wave, which still came rushing
on, black with the mud and slime it had swept from the sea bot-
tom. Those who witnessed its progress from the upper balconies
of their houses, and presently saw its black mass rushing close


beneath their feet, looked on their safety as a miracle. Many
buildings were indeed washed away, and in the low lying parts of
town there was a terrible loss of life. After passing far inland the
wave slowly returned seawards, and strangely enough, the sea,
which elsewhere heaved and tossed for hours after the first great
wave had swept over it, here came soon to rest.

"At Callao a yet more singular instance was afforded of the
effect which circumstances may have upon the motion of the sea
after a great earthquake has disturbed it. In former earthquakes
Callao has suffered terribly from the effects of the great sea wave.
In fact, on two occasions the whole town has been destroyed, and
nearly all its inhabitants have been drowned, through the inrush
of precisely such waves as flowed into the ports of Arica and Chala.
But upon this occasion the center of subterranean disturbance
must have been so situated that either the wave was diverted from
Callao, or more probably two waves reached Callao from different
sources and at different times, so that the two undulations partly
counteracted each other. Certain it is that although the water
retreated strangely from the coast near Callao, insomuch that a
wide tract of the sea-bottom was uncovered, there was no inrush-
ing wave comparable with those described above. The sea after-
wards rose and fell in an irregular manner, a circumstance con-
firming the supposition that the disturbance was caused by two
distinct oscillations. Six hours after the occurrence of the earth-
shock, the double oscillations seem for awhile to have worked
themselves into unison, for at this time three considerable waves
rolled in upon the town. But clearly these waves must not be
compared with those which in other instances had made their
appearance within half an hour of the earth- throes. There is
little reason to doubt that if the separate oscillations had rein-
forced each other earlier, Callao would have been completely de-
stroyed. As it was, a considerable amount of mischief was effected ;
but the motion of the sea presently became irregular again, and so
continued until the morning of August 14, when it began to ebb
with some regularity. But during the 14th there were occasional


renewals of the irregular motion, and several days elapsed before
the regular ebb and flow of the sea were resumed."

In this excellent account of the great sea wave at Arica,
August 13, 1868, Proctor makes no allusion to the U.S.S. Fredonia,
which was lying at anchor with the Water ee; and we add therefore
that the Fredonia is reported to have been capsized as the wave
advanced, and nothing was ever again heard of her, all the officers
and crew having been lost with the wreck of the vessel.

The Water ee was but little injured, and afterwards served as a
hotel. The picture of the stranded Water ee here reproduced was
made by an officer who visited the scene sometime after the dis-
aster. This valuable historic photograph has been preserved by
Mrs. E. V. Cutts of Mare Island, to whom the author is indebted
for this impressive illustration of the effects of this great sea wave.
The previous illustrations show the city of Arica before this earth-
quake, and the mere wreckage which remained after the inunda-
tion of the sea.

In an earlier passage than that above cited, Proctor quotes
the description of an eye-witness, which tells of the movements
of the ships:

"The agent of the Pacific Steam Navigation Company, whose
house had been destroyed by the earth-shock, saw the great sea
wave while he was flying towards the hills. He writes: * While
passing towards the hills, with the earth shaking, a great cry went
up to heaven. The sea had retired. On clearing the town, I
looked back and saw that the vessels were being carried irresistibly
seawards. In a few minutes the sea stopped, and then arose a
mighty wave fifty feet high, and came in with a fearful rush,
carrying everything before it in terrible majesty. The whole of
the shipping came back, speeding towards inevitable doom. In
a few minutes all was completed every vessel was either on
shore or bottom upwards/ "


6. Pratt' s reasoning on the density of the matter under the
ocean, plains and mountains, and its application to India and the

Pratt's reasoning in regard to the density of the matter in
and beneath the crust of the earth, and its bearing on the new
theory of earthquakes is described in my paper on "The Cause
of Earthquakes, Mountain Formation and Kindred Phenomena
Connected with the Physics of the Earth," published in the Pro-
ceedings of this Society for 1906, pp. 344-346. His main con-
clusion is stated thus:

"This (deflection of the plumb line) shows that the effect of
variations of density in the crust must be very great in order to
bring about this near compensation. In fact the density of the
crust beneath the mountains must be less than that below the
plains, and still less than that below the ocean-bed." (Pratt,
Figure of the Earth, 3d edition, Art. 137, pp. 134-135).


"The conclusion at which we have arrived in Article 137, that
the parts of the crust below the more elevated regions are of less
density, and the parts beneath the depressed regions in the ocean
are of greater density than the average portions of the surface,
seems to bear additional testimony to the fluid theory. For it
shows, that notwithstanding the varied surface, seen at present
in mountains and oceans, the amount of matter in a vertical prism
drawn down at various places to any given spheroidal stratum is
the same, although its length varies from place to place as the
earth's contour varies/' (idem, p. 162).

This subject of the density of the matter hidden from our
view beneath the crust of the earth has also been discussed by the
late Professor Henri Poincare, in an address on French Geodesy,
translated by Professor George Bruce Halstead, and published in
the Popular Science Monthly for February, 1913. The eminent
French geometer reasons as follows:

"But these deep-lying rocks we cannot reach exercise from
afar their attraction which operates upon the pendulum and




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deforms the terrestrial spheroid. Geodesy can therefore weigh
them from afar, so to speak, and tell us of their distribution. Thus
will it make us really see those regions which Jules Verne only
showed us in imagination.

"This is not an empty illusion. M. Faye, comparing all the
measurements, has reached a result well calculated to surprise us.
Under the oceans, in the depths, are rocks of very great density;
under the continents, on the contrary, are empty spaces.

"New observations will modify perhaps the details of these

"In any case, our venerated dean has shown us where to
search and what the geodesist may teach the geologist, desirous
of knowing the interior constitution of the earth, and even the
thinker wishing to speculate upon the past and the origin of this

From this extract it will be seen that the most eminent French
authorities recognize the conclusions first formulated by Pratt
over half a century ago. It only remains to consider the applica-
tion of Pratt 's theorem to the Himalayas and the plateau of Tibet.

If, as Pratt says, "the density of the crust beneath the moun-
tains must be less than that below the plains, and still less than
that below the ocean bed," it is very difficult to see how this could
have come about except by the greater uplift of the mountains,
by the injection of more light material beneath, while a less amount
of such material has been injected under the plains, and scarcely
any has remained under the ocean bed, because it tends to work
out by the path of least resistance. This is the only explanation
which satisfies the observed phenomena, and conforms to the
known fact that the mountains and plateaus are uplifted by the
expulsion of matter from beneath the sea, in world-shaking earth-
quakes. Thus the known facts of geodesy as respects the Hima-
layas are fully explained. And the explanation rests on principles
established by a variety of mutually confirmatory observations.


7. Defects in the Doctrine of Isostacy as commonly stated.

The doctrine of Isostacy as commonly stated is vitiated by a
serious if not fatal error; and it is necessary to overcome this
defect if the doctrine is to hold its place in modern thought. In
Science of February 10, 1911, Professor J. F. Hay ford presents a
paper based on the valuable data he obtained in the work of the
U.S. Coast and Geodetic Survey deduced from seven hundred and
sixty-five series of astronomical observations at eighty-nine sta-
tions in the United States. The causes assigned, however, are so
inadequate that it seems worth while to point out the defects in
his reasoning, which is as follows:

"Columns A and B have been assumed to contain equal masses.
There is complete isostatic compensation. The pressures at the
bases of the two columns are equal, and at any less depth, X, the
pressure is greater in A than in B. Now assume that in the nor-
mal course of events a large amount of material is being eroded
from the high surface of column A and deposited on the low sur-
face of column B. After this erosion has been in progress for some
time the isostatic compensation will no longer be perfect. The
pressure at the base of B will be greater than at the base of A. The
pressure very near the top of B will still be less than at the same
level in A so long as the top of A remains higher than the top of B.
There will be some intermediate level at which the pressure in
the two columns is the same. Call this level of temporary equality
of pressure in the two columns the neutral level. As the process
of erosion and deposition progresses the neutral level will gradu-
ally progress upward from its original position at the base of the
columns. Eventually if no interchange of mass took place between
the columns except at the surface, and no vertical displacement
occurred in either column, the neutral level would reach the sur-
face when the process of erosion and deposition became complete
and the upper surfaces of the two columns were at the same level.
During the process of erosion and deposition the excess of pressure
in A at any level above the neutral level will continually decrease.


Similarly, at any level below the neutral level the excess of pres-
sure in B will continually increase as the erosion progresses and
the neutral level will rise. Thus there will be established a con-
tinually increasing tendency for the material below the neutral
level in B to be squeezed over into A. If the stresses tending to
produce this undertow from the lower part of B to A become
greater than the material can stand, the flow will take place as
indicated by the arrow in the figure. If the material flows with-
out change of volume, as if it were incompressible, the upper part
of A and its surface will be raised, the upper part of B and its sur-
face will be lowered, the neutral level will sink and an approxi-
mation to the original conditions with complete isostatic com-
pensation will be re-established.

"This is the general case of isostatic readjustment by the
action of gravitation alone. Gravitation tends to produce a deep
undertow from the regions where deposition is taking place to the
regions where erosion is in progress, in the direction opposite to
that of the surface transfer of material.

"Let us suppose that the isostatic compensation at a given
stage in the earth's history is practically complete for a
continent, that the process of erosion from the greater part of
the continent and deposition around its margins is in progress,
and that the process of readjustment by a deep undertow is in

The fatal defect in this reasoning consists in the fact that it
begs the question, and does not in any way explain the elevation
of the margin of a continent, but only how it may maintain its
present form by a process of readjustment. This is like a river
rising higher than its source, a man trying to lift himself by pull-
ing on his boot-straps, or the logician reasoning in a circle. For in
order to explain the development of the inequalities of the earth's
crust, we must not only explain the adjustment and balancing
between adjacent parts, but also how the original uplift came about,
to give the observed contrast in surface levels.


Now on the premises used by Hayford, it is possible to explain
how a given inequality of surface levels, when once existing, can
be maintained; but it is not possible to account for the origin of
the inequalities of level. Isostacy as thus depicted is not an active
creative agency, but simply a negative process for maintaining existing
inequalities. Under the doctrine as above stated, the height of a
mountain or plateau could never increase, for that would require
the exertion of positive elevating forces, not mere balancing for
maintaining inequalities of levels already existing.

Accordingly, this formulation of the doctrines of Isostacy is
defective, and inadequate to account for the phenomena of the
earth's crust.

The true doctrine should include not only the balancing pro-
cess described by Hayford, but also those elevating forces directed
from the sea, by which the mountains are elevated as narrow walls
about the borders of continents, on the great plateaus which spread
out as wider embankments beneath them. Without these posi-
tive uplifting forces, no continent could ever have a mountainous
border thrown up about it.

No doubt the elevation is produced under approximately
isostatic conditions. Mountains can be forced up only to a cer-
tain height, the transfer of lighter material under the higher parts
thus giving nearly equal mass in all equal prisms drawn to the
center of the earth. The path of least resistance is towards regions
of elevation, and the underlying material expands as the surface
level is forced up. If this were not so the greater weight under
the elevated region would cause it to subside to the common level.
In this way, and in this way only, can progressive elevation be

The weakness of the old method of reasoning is further illus-
trated by Hay ford's remarks:

"Under a region of deposition two effects of opposite sign
tend to occur. The effect of increased pressure tends to produce
chemical changes accompanied by decrease of volume and so to
produce a sinking of the surface. The blanket of deposited mate-

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rial tends to raise the temperature in each part of the material
covered, to increase the volume of this material, and thereby to
raise the surface. The temperature effect may serve in time to
arrest the subsidence caused by increased pressure or even to raise
the surface and change the region of deposition into one of erosion.

"The changes of temperature just described are due directly
to erosion and deposition. If as an effect of erosion and deposi-
tion an undertow is started tending to re-establish the isostatic
condition, this undertow, a flow of material presumably solid,
necessarily develops considerable heat by internal friction. The
increase of temperature so produced tends to cause an increase of
volume. It may favor new chemical changes, including changes
from the solid to the liquid state, which may be accompanied by
a change of volume. The undertow tends to be strongest not
under the region of rapid deposition, but under the comparatively
neutral region between the two in which neither erosion nor deposi-
tion is much in excess of the other, see Figure 2. Hence the under-
tow by increasing the temperature and causing a change of density
may be directly effective in changing the elevation of the neutral
region between two regions of deposition and erosion.

"Horizontal compressive stresses in the material near the
surface above the undertow are necessarily caused by the under-
tow. For the undertow necessarily tends to carry the surface
along with it and so pushes this surface material against that in
the region of erosion, see Figure 2. These stresses tend to pro-
duce a crumpling, crushing and bending of the surface strata
accompanied by increase of elevation of the surface. The increase
of elevation of the surface so produced will tend to be greatest
in the neutral region or near the edge of the region of erosion, not
under the region of rapid erosion nor under the region of rapid

The criticism against this reasoning is the same as that used
above namely, it will explain only balancing, but not the up-
lifting of great mountain walls along the sea coast. Nothing but
the transfer of lava from beneath the sea, and the expansion of it


under the mountains will explain the observed mountain walls
along the borders of continents; and this requires positive forces of
elevation, not mere negative processes. The advocates of Isostacy,
as heretofore taught, have left that doctrine with such a serious
defect that this correction is necessary to give it a rational basis.

8. The uplifting of the Himalayas, Arrakan and Afghanistan
Ranges explains the great Asiastic earthquake belt. Confirmation of
Colonel Burrard's impressions that the Himalayas have been pushed
northward, but not by a change in the rotation period of the earth.

We have seen that the region now occupied by the rivers
Indus and Ganges was formerly a sea valley; and that after the
Himalayas were elevated to a great height, the valley itself was
slowly raised above the ocean.

If proof is asked that the valleys of the Indus and Ganges
were formerly below the sea, it is furnished by the well established
fact that such valleys as the San Joaquin and Sacramento in
California were below the sea when the Sierras were being elevated.
What has happened in California has also happened in India; and
the same process of elevation will eventually give a fertile habitable
valley in the belt just south of the Aleutian Islands now covered
by a sea nearly five miles deep.

This proof that the valleys of the Indus and Ganges once were

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Online LibraryW. L. (William Larkin) WebbBrief biography and popular account of the unparalleled discoveries of T.J.J. See .. → online text (page 14 of 28)