have been but banks of cloud； since； having been in the plane of
the planet's equator at the time； we had naturally but a very
oblique view of the poles； while the absence of glacial scratches
shows； I take it； that though the axis may have been a good deal
more inclined than at present； it has not； at all events since
Jupiter's Palaeozoic period； been as much so as that of Uranus or
Venus。 The land on Jupiter； corresponding to the Laurentian
Hills on earth； must even here have appeared at so remote a
period that the first surface it showed must long since have been
worn away； and therefore any impressions it received have also
been erased。
〃Comparing this land with the photographs we took from space； I
should say it is the eastern of the two crescent…shaped
continents we found apparently facing each other。 Their present
form I take to be only the skeleton outline of what they will be
at the next period of Jupiter's development。 They will； I
predict； become more like half moons than crescents； though the
profile may be much indented by gulfs and bays； their superficial
area being greatly increased； and the intervening ocean
correspondingly narrowed。 We know that North America had a very
different shape during the Cretaceous or even the Middle Tertiary
period from what it has now； and that the Gulf of Mexico extended
up the valley of the Mississippi as far as the Ohio； by the
presence of a great coral reef in the Ohio River near Cincinnati。
We know also that Florida and the Southeastern Atlantic States
are a very recent addition to the continent； while the pampas of
the Argentine Republic have； in a geological sense； but just been
upheaved from the sea； by the fact that the rivers are all on the
surface； not having had time to cut down their channels below the
surrounding country。 By similar reasoning； we know that the
canon of the Colorado is a very old region； though the
precipitateness of its banks is due to the absence of rain； for a
local water…supply would cut back the banks； having most effect
where they were steepest； since at those points it would move
with the greatest speed。 Thus the majestic canon owes its
existence to two things： the length of time the river has been at
work； and the fact that the water flowing through it comes from
another region where； of course； there is rain； and that it is
merely in transit； and so affects only the bed on which it moves。
Granting that this is the eastern of the two continents we
observed； it evidently corresponds more in shape to the Eastern
hemisphere on earth than to the New World； both of which are set
facing one another； since both drain towards the Atlantic Ocean。
But the analogy here holds also； for the past outlines of the
Eastern hemisphere differed radically from what they are now。
The Mediterranean Sea was formerly of far greater extent than we
see it to…day； and covered nearly the whole of northern Africa
and the old upheaved sea…bottom that we see in the Desert of
Sahara。 Much of this great desert； as we know； has a
considerable elevation； though part of it is still below the
level of the Mediterranean。
〃Perhaps a more striking proof of this than are the remains of
fishes and marine life that are found there； is the dearth of
natural harbours and indentations in Africa's northern coast；
while just opposite； in southern Europe； there are any number；
which shows that not enough time has elapsed since Africa's
upheaval for liquid or congealed water to produce them。 Many of
Europe's best harbours； and Boston's； in our country； have been
dug out by slow ice…action in the oft…recurring Glacial periods。
The Black and Caspian Seas were larger than we now find them；
while the Adriatic extended much farther into the continent；
covering most of the country now in the valley of the Po。 In
Europe the land has； of course； risen also； but so slowly that
the rivers have been able to keep their channels cut down； proof
of their ability to perform which feat we see when an ancient
river passes through a ridge of hills or mountains。 The river
had doubtless been there long before the mountains began to rise；
but their elevation was so gradual that the rate of the river's
cutting down equalled or exceeded their coming up； proof of which
we have in the patent fact that the ancient river's course
remains unchanged； and is at right angles to the mountain chain。
From all of which we see that the Eastern hemisphere's crescent
hollowof which； I take it； the Mediterranean； Black； and
Caspian Sea depressions are the remainshas been gradually
filled in； by the elevation of the sea's bottom； and the
extension of deltas from the detrital matter brought from the
high interior of the continents by the rivers； or by the combined
action of the two。 Now； since the Gulf of Mexico has been
constantly growing smaller； and the Mediterranean is being
invaded by the land； I reason that similar causes will produce
like effects here； and give to each continent an area far greater
than our entire globe。 The stormy ocean we behold in the west；
which corresponds to our Atlantic； though it is far more of a
mare clausum in the geographical sense； is also destined to
become a calm and placid inland sea。 There are； of course；
modifications of and checks to the laws tending to increase the
land area。 England was formerly joined to the continent； the
land connecting the two having been rather washed away by the
waves and great tides than by any sinking of the English
Channel's bottom； the whole of which is comparatively shallow。
Another case of this kind is seen in Cape Cod and the islands of
Martha's Vineyard and Nantucket； all of which are washing away so
rapidly that they would probably disappear before the next
Glacial period； were we not engaged in preventing its recurrence。
These detached islands and sand…bars once formed one large
island； which at a still earlier time undoubtedly was joined to
the mainland。 The sands forming the detached masses are in a
great processional march towards the equator； but it is the
result simply of winds and waves； there being no indication of
subsidence。 Along the coast of New Jersey we see denudation and
sinking going on together； the well…known SUNKEN FOREST being an
instance of the latter。 The border of the continent proper also
extends many miles under the ocean before reaching the edge of
the Atlantic basin。 Volcanic eruptions sometimes demolish parts
of headlands and islands； though these recompense us in the
amount of material brought to the surface； and in the increased
distance they enable water to penetrate by relieving the interior
of part of its heat； for any land they may destroy。〃
CHAPTER XI。
A JOVIAN NIAGARA。
Four days later； after crossing a ridge of mountains that the
pressure on the aneroid barometer showed to be about thirty…two
thousand feet high； and a stretch of flat country a few miles in
width； they came to a great arm of the sea。 It was about thirty
miles wide at its mouth； which was narrowed like the neck of a
bottle； and farther inland was over one hundred miles across； and
though their glasses； the clear air； and the planet's size
enabled them to see nearly five hundred miles； they could not
find its end。 In the shallow water along its shores； and on
the islands rising but a few feet above the waves； they saw
all kinds of amphibians and sea…monsters。 Many of these were
almost the exact reproduction in life of the giant plesiosaurs；
dinosaurs； and elasmosaurs； whose remains are preserved in the
museums on earth。 The reptilian bodies of the elasmosaurs；
seventy…five feet in length； with the forked tongues； distended
jaws and fangs of a snake； were easily taken for the often
described but probably mythical sea… serpent； as partially coiled
they occasionally raised their heads twelve or fifteen feet。
〃Man in his natural state；〃 said Cortlandt； 〃would have but small
chance of surviving long among such neighbours。 Buckland； I
think； once indulged in the jeu d'esprit of supposing an
ichthyosaur lecturing on the human skull。 'You will at once
perceive；' said the lecturer； 'that the skull before us belonged
to one of the lower order of animals。 The teeth are very
insignificant； the power of the jaws trifling； and altogether it
seems wonderful how the creature could have procured food。'
Armed with modern weapons； and in this machine； we are； of
course； superior to the most powerful monster； but it is not
likely that； had man been so surrounded during the whole of his
evolution； he could have reached his present plane。〃
Notwithstanding the striking similarity of these creatures to
their terrestrial counterparts that existed on earth during its
corresponding period； there were some interesting modifications。
The organs of locomotion in the amphibians were more developed；
while the eyes of all were larger； the former being of course
necessitated by the power of gravity； and the latter by the
greater distance from the sun。
〃The adaptability and economy of Nature；〃 said Cortlandt； 〃have
always amazed me。 In the total blackness of the Kentucky Mammoth
Cave； where eyes would be of no use to the fishes； our common
mother has given them none； while if there is any light； though
not as much as we are accustomed to； she may be depended upon to
rise to the occasion by increasing the size of the pupil and the
power of the eye。 In the development of the ambulatory muscles
we again see her handiwork； probably brought about through the
'survival of the fittest。' The fishes and those wholly immersed
need no increase in power； for； though they weigh more than they
would on earth； the weight of the water they displace is
increased at the same rate also； and their buoyancy remains
unchanged。 If the development of life here so closely follows
its lines on earth； with the exception of comparatively slight
modifications； which are exactly what； had we stopped to think；
we should have expected to find； may we not reasonably ask
whether she will not continue on these lines； and in time produce
beings like ourselves；