Evening star. [volume] (Washington, D.C.) 1854-1972, 1906-07-03
ANCIENT SCOTTISH VOLCANOES.
Research at Rosyth Results in Some
Remarkable Finds.

RcudkhAO4o e Illus.
From the Edinburgh Scotsman.
A rock section Of some geographical inter-
est may be seen on the new railway Of Ro-
syth In cutting that has been driven
through the ridge at Limpetness, on tho
west side Of st. Margaret's bay. The rock
In the immediate vicinity Is whinstone; one
is surprised after penetrating the whin
short distance to find strata OF totally
different character At the west side Of the
section nearest Rosyth Castle there Is a
large mass OF whinstone; abutting against
this is thick bed of volcanic tur which
dips to the east and passes under O seam of
limestone. The latter in turn is overlapped
by a bed Of shale. while the outer facing on
the east side of the ridge Is sloping bed
of trap rock. From its harsh feel coarse
texture and mixed ingredients. this tun may
be at once recognized as very characteris-
tic example Of volcanic tuff agglomerate
1t Is made up Of scoriae. punlice and other
fragmentary materials. such as are dis
charged by volcanoes and are often found
filling up old volcanic necks. Lines OF STRAIT
tfcatlon indicate that the constituents OF
the turf owe their arrangement IN part to
the action Of the waves currents: they
must therefore. have been thrown out of a
submarine volcano or fallen in showers into
water. At the deepest part of the cutting,
where the ridge Is the highest, irresistible
evidence convinces the observer that he is
here practically inside an old volcano SEQ
riae and other loose materials brought to
the surface and piled up in cones afford
proof of the explosive character of an erup-
ton. Volcanic explosions are caused by
steam; geysers and volcanoes are in all
their essential characters alike, except that
the geyser discharges hot water instead of
lava. AS molten rock reaches the surface
volumes or steam escape, because OF the d.
unfinished pressure. The bursting gas bub-
Dles also disspate the fluid rock into I'M
palpable powder, which may be projected
to great height and becomes widely dis
tributed by the wind. Volcanoes Of the ex-
plosive type discharge comparatively little
lava, and in some cases none at ALL
Bearing in mind that the volcanic tufY is
superficial deposit of materials produced by
explosions. we can form some idea Of the
conditions under which IL was accumulated
The explosive eruptions must have been
long continued to furnish maerials for a de-
post OF this thickness, but the period OF
quiescence which ensued after they ceased
was probably OF much longer duration
for in the Immediately succeeding layers of
strata no trace of volcanic action can be
discovered. One of the peculiaritiss or vol
canio agencies Is its Rip Van Wrinkle char
acter Vesuvfus remained inactive all
through Roman history down to ~ A. d
when the eruption occurred by which POM
peii and Herculaneum were overthrown
But TOO OF even 1000 years would not 20
very far to account for forty feet of sedi-
mentary rock. The time OF tranquility.
however, came to an end at last: the vol
canic forces once more awoke. but their
character was altered. the explosive being
exchanged for the effusive type; instead of
showers of stones and ashes great streams
of lava were now sent up from the interior
of the earth. One feature In the section ia
the remarkably even outcrop Of the sedi-
mentary beds. which look as though their
ends had been planned of to make a FER
fectly horizontal surface. The most proba-
BILE explanation Is that 1t formed part of the
internal surface, Of the volcanic vent. and
that the ends Of the beds were sawn of by
explosive blasts issuing from the mouth Of
the volcano. Up this inclined surface too
the stream of lava has been forced and In
truded over the shale- In any case. the
displacement has been subsequent to the
intrusion Of the trap; the upheaval has az
fected tun. limestone. shale and trap alike
The cause of this upheaval is perhaps to be
found in the upward pressure of a great
body OF molten rock which at a much later
date found vent for itself through the loose
materials forming the old volcanic funnel
and at the same time greatly enlarged that
opening. The mass OF whinstone at the
west end OF the cutting Is a memorial Of
this later outburst. Rising vertically
through the tuff as an Irregular column ar
unknown depth. It's intrusive origin Is obyi-
Gus. Without doubt the whinstone here IA
simply plug of lava left in the. pipe or
fissure through which long before the mate
rails OF the tuff and trap beds were erected
The tunnels Of many ancient volcanoes are
found plugged with lava in this way.