The Pacific commercial advertiser. [volume] (Honolulu, Hawaiian Islands) 1856-1888, 1867-02-02
Commercial Advertiser.
correspondence.
CoycoRD. Mass., Dec. :, 1866.


October lst. we have had a few frosts and stiien-
ing at night Of the moist ground, but the ther-
mometer has seldom dropped below SO after
sunrise; and for nine weeks past we have had
more sunshine than | ever witnessed, in the same
period, ut the same season, at Honolulu.
Prof. AgIssiz has just closed his lectures On
the Amazon In Speaking Or the physical his
tory of South America. the Professor said it had
become axiom Of geology that - the highest
mountains We're the most recent - and that the
table lands OF Guri'tna and the high lands Of
Brazil older than the Andes. The recent
uphe.val of the Andes showed that the trough
No. formed by them. open to the Pa
cGc. The slopes of the mountains. dipping to-
ward the north, contain deposits belonging to the
transition period. The valley Of the Amazon
had many of the characteristics Of the Mississippi
formed by the uphesIval of the I-aurentan hills
in tine north, trendinS east and west. Next the
uphcaval Of the Alleghanies, trending north and
south, leaving the plain of the Ohio open to the
Pacific and lastly the upheaval Of the Rocky
Mountains, forming the trough of tile Mississippi
lt was an interesting question how far the
trough was lined with cretaceous deposits. One
geological feature of the valley Of the Amazon
(which received its present outline since the
taceous period) distinguishes it from all other
parts of the world. and that is the absence Of any
indications Of alternate upheaval and depression
in the formation of the land. North of the ANA
zon-between Almeirim and Obidos-there is a
remarkable series of hills. with level SUBMITS of
considerable extent, and between these plate;lus
intervening hills, with rounded domes. The
cause of this roundress was disintegratOn by
rains. Other ranges caused by upheavals,
shown by the dip Of their strata But
here the strata perfectly horizontal. The
height Of these hills is determined by the height
of the strata which offers the greatest resistance
to disintegratiOn. On the opposite side of the
river there another series of similar plateaus
and hills. These bIllOws, the Professor thinks,
once extended over the entire valley of the ANA
zOn. and could have been formed only by depO-
sits in an enclosed basin with isolatng walls.
The walls still exist the north and on the
sOuth-the Andes forming the western wall.
But there is wall found the east. where
the valley is open to the sea.
The bed of the Amazon consists of perfectly
horizontal stratified laminated cretaceOus clay.
covering an area of 1000 miles in length by 500
to 200 miles in width above the clay is found
stratiied sandstone rising to hight of 300 to
500 feet, and over this an ochraceous loam, mixed
with bOulders, forming the series of plateaus
with intervening valleys and rounded hills, al
ready described above.
Professor Agassiz had doubt that the
once bathed the base Of the Andes but since the
dry land first rose in the valley it could not be
said that the ocean again covered it, because in
the deposits. over this large area, remains of
marine plants had ever been found. ~ vast sheet
Of water must have filled the valley Of the
Amazon. a. the horizontal strata Of laminated
clay could only have been produced by gradual
precipitation. Professor Agissiz rejects the hy-
pothess of an immense fresh water lake. because
he has been unable To find any fossil remains in
these deposits of fresh water animals. such as
found in the ISIe of Wight in the South Of
France and at the foot of the Rocky Mountains.
The stratifed deposits Of the Amazon must. there
for have been formed under very peculiar cir
cumstances-not by the existence of large
oceanic OF fresh water lake, - has already been
shown - but. as Prof. Aga-siz explained the
phenomena, by the introduction of glaciers-Of
the former existence of which he found unInis-
taxable traces the thickness of these glaciers he
estimated at 10000 TO $1,000 feet. CIn New
England the height Of the glaciers estimated
at g 900 feet.) There was evidence also that by
glacial action a vast mOraine had been formed, or
set WALL on t!r asst Of the valley of the Amaz' IN,
rendering the isolation of the great basin com
plete or 1t might be that the ocean itself was
frozen over. and that the glaciers, or the land.
the ice barrier the coast. The thinnesS
OF the laminated clay strata indica - very gen
tie movement of the water ut the time of Its form
nation. The second series of coarse grained
sandstone indicated period of great cJmmotIOn
Of the waters, and the third deposit of minute
NEUTRALITY-SUSPICIOUS. loam-indicated restored
tranquility. In Il great glacier, covering the
whole valley, could bs found all the conditions
necessary to produce these results, which could
he accounted for in other way. Under a mild
temperature the first result would be, the
cumulation Of water underneath, from which,
protected from outside commOtion, minute par
tie!es only could be deposited. Such materials
were found in the laminated clay, ground to
powder by the motion of the glacier Besides
bouIders, glaciers are found TO contain all kinds
Of earthly materially
Under an increase of temperature tie glacier
would melt more rapidly, and larger accumula-
tions of water would be formed, pr Oducing floods
AMI currents with violent commotiOn of the
waters, resulting in the deposit Of coarse sand
stone When the water began to flow of 1t
would sweep away large proportion of the finer
materials and this would account for the ls"la-
tIOn and denudation Of the hills between AiIneI-
rim and Obdos. The same strata, as existed IN
these hills, mast once have extended throughout
the valley, and the Ochraceous loan must have
been deposited after the greater part of the sand
stone had been removed. n i proven by the fact
that it fills the INEQUALITIES of the surface caused