New-York tribune., 1903-01-29

4 complete geological history of this State
cannot be written until various researches in
adjacent regions are pushed further 1t would
have been mistake, though, TO wait for that
consummation before undertaking the present
task A large amount Of material was already
available. Professor Tarr, moreover. is well
fitted TO its satisfactory performance. He has
wide familiarity with the Investigations of other
biologists; he has done much original work him
self, and he shows both penetration and a Ju-
dicial temperament in handling matters about
which there is dispute. He may well be re-
gar1ed worthy follower of Hall and Newberry-
Few physical features of the country are so
Impressive as mountains. The Adirondacks are
st present the highest, and with one uifiing ex-
ception they are the oldest Of such elevations IN
the Empire State. Prior 20 the appearance OF
the earliest and lowest forms Of life in this part
OF the world there were mountains in New-Jer-
sey and in the immediate vicinity of the site OF
the metropolis. AT that time, says Professor
Tarr there were peaks where now New-York
City stands which rivalled in height any
existi-g elsewhere to-day The Atlantic High
lands and Ramapo Mountains, in RockIano
County, " Y are Insignificant relics OF 1ha'
venerable range The Taconic Mountains sun
discernible up near the Massachusetts boundary
and in Verne Mt, formed at a later DATE
and the Appalachian uplift. TO which belong
Kittaninny. in New-Jersey, and certain consio-
erable hills in Orange and Sullivan counties
n. Y. are lii you-ger. Strictly speaking. the
Catskiils are not mountains at ALL having
been produced by the crumbng of originally
level strata They are the remains Of a weather
sculltured plateau The sandstone composing
them was deposited as sediment the bed OF
an OLD ocean which covered nearly the
whole State, and in which the Adirondacks a-d
m southeastern highland rose as mighty ISL
snds Subsequently, immense area was lifted
without contortion. and the proce $ Of carvin1
by TIE clements began.
In very much more recent times the State
overspread by an ice sheet which extended
hither from Labrador Professor Tarr refrains
from giving figures concerning the beginning
and duration of the glacial epoch, but he dis
cusses the effects Of this visitation at great
length The ice sheet deepened existing valleys.
notably those Of the finger lakes in western
York: deposited beds OF clay, which are
nothing but paste made out of rock -four; left
great ridges of -rave to mark the limits Of its
advance; dropped huge bowlders which were
sometimes transported great distances; cut
scratches that are still visible many noun
tain and hill top; and by damming previously
existing streams caused them to find new
channels.
Professor Tarr views with favor the opinion
that the Great Lakes the product Of four
agencies: Valley cutting by air and water p
TO the glacial epoch. erosion by ice, the opening
Of new routes for the escape Of the water by
the damming Of old channels (either with ice or
the gravel of that period). and a change of level
by a slight fitting OF a wide The Cornell
professor believes that the various lake basins
partially formed before the glacial epoca,
and that the deepening influence Of the ice was
PARTICULARLY active in giving Ontario its present
size. becar the Adrondacks must have di-
Verted westward much OF the advancing sheet
originally. perhaps the Upper Lakes discharged
into the Mississippi Valley. Access thereto be-
coming stopped. ar the retreat of the ice hav
ope4-ed a way eastward, the whole chain
may have found - outlet through the Mohawk
and Hudson, the former then having communi-
cation with Lake Ontario AS the ice sheet
shrank still further, Lakes Superior, Michigan
and Huron We're able TO reach the. ST. Lawrence
by way of Nipissing Lake and Ottawa River.
Some cause Yet unknown-a change of the level
in Canada perhaps-at length sent the water
around by way Of Lakes Erie and Ontario. Be
tween the two latter there had previously been
some connection; but Niagara was now called
upo- render an unprecedented service-to
convey volume fully half as great as that
which flows past New-Orleans.
Many geologists have wrestled with the cues
tion Of the age of Niagara Falls The opinion
expressed by DIR. James Hail. that the cataract
was originally seven miles further down stream
but had slowly receded. is accepted without dis
pute, and this theory the basis of all chrono-
logical calculations. Since the present rate of
wear at the Horseshoe Fall is about three feet
a century. there seems to be a prima face case
for ten thousand year estimate. Professor Tarr
points out, however, that there various ele-
ments of varia bility which cannot be determined
with precision. The layer of limestone whose
wearing allowed the cataract to retreat is thin
ner in the lower part Of the gorge than it is at
the falls, and il might we'll have succumbed
more rapidly at earlier period than it does
now The gorge varies in width, too, so that the
rate Of recession would be affected by another
cause Moreover, Professor Tarr thinks that
there was already some channel there before the
glacial period. and that less cutting would be
required than if the work all done after the
closing of the Nipssng Ottawa outlet The
more the problem is studied the more complex
does il become Guesses as to the time con-
sumed IN the formation of the Niagara gorge
range all the way from five thousand to fifty
thousand years. II may be possible q tell
which guess is nearest right until more is known
about the duration of the outflow through Can
ada. 10 which geologists may yet obtain a clew
II is conceded that the Canadian Fail is re-
treating faster than the the American
side and that eventually the latter will cease TO
exist. There is evidence, moreover that the
land in hat part of the country is rising rela-
I ely while in the vicinity of Chicago it is
sinking. If these changes continue at the
present rate the whole lake system will empty
into the Mississippi five thousand years hence!
5urroqa1ee aotlres