The sun. [volume] (New York [N.Y.]) 1833-1916, 1882-07-09

lively little value. NJ. W. ii.
RambIes OF Geologist.
Under the title OF Geological Sketches Mr..
ARCHIBALD GErKrE has collected. and Messrs.
Macmillan have reprinted number Of essays
published during the last few years. most of
which are records OF journeys and excursions
made in the prosecution OF the authors geolog
cal inquiries. How wide has been the range
of Mr.. Geikics personal investigations is at
tested by tho subjects Of these papers. which
include accounts OF tho volcanoes Of central
France. OF the old glaciers OF Norway and Scot
land. and of interesting geological features in
the scenery OF the Orkneys. together with
studies OF the Yellowstone geysers and Of the
so-called bad lands" OF Wyoming Territory.
In connection with his remarks on the latter
phenomena, the author points out how
promptly and completely the erosive theory
would have trlumphed over the cutas-
trophic or convulsionist hypothesis had the
science Of geology been evolved on the west
side Of the Rocky Mountains. instead OF in
western Europe. As regards an appreciation
OF the real efficacy of superficial erosion in the
development Of terrestrial surface European
biologists have been at great disadvantage.
for the rocks in that region have been SUBJ
jected to so many changes that the effects OF
superficial waste have been masked by those of
SuDIbTTAnetn ulSluTDtHce VII lllc OllleE uiillu,
the Pacific slope OF the North American con-
tinent has not been buried under the sea for a
long succession of geological periods and over
thousands Of square miles the strata remain
substantially unmoved from their original
horizontal positions SO that the effects of sur
face erosion can be detected at a glance upon
their fiat parallel layers. Mr.. Geikie looks
upon the whole country west of the Rocky
Mountains as one vast geological model, TO
which the world should come in order to learn
the fundamental laws of dcnudation.
In all OF the essays whose scope and purport
have been indicated the author evlnccs happy
faculty Of eXpOstion. and. taken collectively
they constitute an admirable handbook for the
popularization Of geological truth. To us. how
ever. the most interesting essay in the volume
is that describing the geological influences
which have affected the course OF British
history and by directing special attention to
the results Of this inquiry we can Illustrate the
attractive method and substantial value Of the
companion papers. We arc told, in the first
place that tho British Islands unquestion-
ably still formed part OF the mainland Of Europe
at the time when tho earliest human beings
appeared in the country 1t is equally certain
that although the area Of these islands was
formerly prolonged westward beyond its pros
ent limits there has never been any impor-
tant mass of land to the west Of them
in recent geological times. or within what may
be called the human period. Every successive
wave II migration, therefore. whether Of plant
or animal. must have come from the eastern
side. whore the land undoubtedly spread over
the site Of what is now the North Sea. Even at
the present day an elevation Of less than six
hundred feet would convert the whole OF that
sea into dry land from the north of Shetland to
the hcadands Of Brittany. At the epoch when
l.. D..s. 81,
land the Thames was no doubt tributary OF
the Rhine. which. in its course northward. may
have received other ailluents from the east Of
Britain, before 1t poured its waters into the
Atlantic at n point somewhere between the
heghts.of Shetland and the mountainous
coasts OF southern Norway.
1t was mainly subsistence that produced the
isolation Of Britain. The whole area slowly
sank. until the lower tracts were submerged,
the last low ridge connecting the land with
France was overlooked and Britain became q
group Of islands. PROFESSIONALLY the isola-
| ton was materially promoted by the ceaseless
wear and tear OF the superficial agencies which
| are still busy at the same task. Tho washing
| OF descending rain. tho erosion OF water
courses. and the gnawing Of sea waves all told
| in the long process Of degradation. Thus it was
that laundering from want Of support below
! and eaten away by attacks from above. the low
| lands gradually diminished and disappeared
| beneath the sea. 1t Is obvious that no event in
the geological annals OF Britain can have had a
more powerful influence on the history OF its
| inhabitants than the separation Of the
| country by n considerable channel from the
European Continent. Mr. Geikie thinks that
the last neck Of land which united Britain to
the mainland was that through which the
Strait Of Dover now runs Apart from the
| n1n,,h - -, ,l,a.l,
| Sea area. which is attested by submerged
forests on both sides 1t is easy to perceive how
greatly the widening Of this channel must have
been furthered by the batterns OF waves and
the scour Of strong tidal currents. In spite,
| however, of the subsistence and the constant
erosion. the depression remains so shallow that
its deepest parts are less than $50 feet below
the surface. II. therefore. ST. Paul's Cathedral
| could be shifted from the heart Of London to
the middle Of the Strait OF Dover. moro than
| half Of 1t would rise above water The brilg-
ing Of tho Channel at this point would be an
engineering feat whose difficulties would arise
not from the depth Of the strait. but from tho
vehcmencc Of the tidal currents.
Most Enslshmen would concur with Mr.
Geikie in deeming it great misfortune that
in the course Of the process Of separation from
the mainland by subsistence and erosion Ire.
| land should have become detached from Bri-
tain. We have certainly had ample occasion In
recent years to observe how much this geologl.
cal change has affected the history Of both
countries. That tho isolation Of Ireland took
place before Britain had been cut of from tho
Continents proved by a comparison OF the dis
tributon ofliyinG plants and animals. At the
time when Ireland was segregated. the inter,
val which had elapsed between tho submerEen
cies and ice sheets OF tho glacial period hat
been too short to enable the flora and fauna o.