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4
kortfattet Oversigt over de forskjellige Sedimenters
Fordeling i Havet — støttet til Iagttagelserne ombord og mine
senere Undersøgelser.
Jeg maa her forudskikke den Bemærkning, at jeg i
Mangel af andre Udtryk liar valgt Benævnelsen "Ler" for
alle de Slamdannelser, der efter Tørring opnaaede en vis
Fasthed og Sammenhængskraft. Beskrivelsen af
Bundprøvernes ydre Kjendetegn refererer sig væsentlig til deres
Udseende i den tørrede Tilstand, saaledes som jeg ved
mine Undersøgelser har havt dem. Det være foreløbig
sagt, at det mest karakteristiske Mærke for de forskjellige
Sedimenter er Farven, der væsentlig er betinget af den
Oxydationsgrad, hvori de befinder sig.
I de grundere Dele af Havbunden langs Norges og
Spidsbergens Kyster finder A-i Bunden bedækket af et mere
eller mindre plastisk Ler, der næsten altid er af en graa
Farve. Blandingsdelenes Finhed og Biblandingen af grovere
Materiale — i Form af Sancl, Dyreskaller og lignende —
er meget forskjellige i de talrige Prøver, der er indsamlede
fra disse Egne af Havbunden. Dette Kystler gaar sjelden
dybere ned end til 400—500 Favne (700—900 Meter).
Ved dette Dyb støder man ialmindelighed paa et brunt
Ler, der bebuder Overgangen til det egentlige
Oceansediment. I Begyndelsen af sin Optræden er dette brune Ler
ofte temmelig sandholdigt og grovkornigt og indeholder kun
faa Foraminiferer (Overgangsier); længere ud i Havet bliver
det mere fint og ensartet, indtil clet gaar over i det
saakaldte "Biloculinler". som tindes paa næsten alle Dybder,
eier er større end 1000 Favne.
Dette er et eiendommeligt, fint Sediment af en
lysbrun til mørkbrun Farve og udmærker sig ved sin større
eller mindre Rigdom paa smaa Foraminiferer.
Fremtrædende for det’ blottede Øie er isærdeleshed Slægten
Biloculina med sine smaa hvide Skaller, af Størrelse og Fonn
som et Knappenaalshoved, spredte rundtomkring i Slammet.
Dette er derfor af Zoologerne opkaldt efter disse smaa Dyr,
der giver det et karakteristisk og let kjendeligt Udseende.
Vi skal senere tale om de øvrige i Leret
forekommende Foraminiferer, som paa Grund af sit Udseende eller
sin ringe Størrelse er mindre iøjnefaldende end Biloculinerne,
om de’ end i Antal er langt overveiende.
I den østlige Del af Nordhavet mellem Spidsbergen,
Beeren Eiland, Norge og Novaja Semlja har vi fundet
Bunden bedækket med et grøn-graat paa Dyrelevninger
fattigt Ler. Dets grønlige Farve og øvrige karakteristiske
Egenskaber er isærdeleshed udprægede i Bundprøverne fra
de østligste Stationer. Zoologerne har kaldt dette Sediment
Atlantic Expedition. I will briefly state the results of the
preliminary inspection and my own subsequent examination
in so far as they bear on the distribution of the deposits
over the bed of the ocean-traCt explored.
To begin with, I must observe that for want of some
other, more precise expression. I have chosen the term
•’clay" by which to designate all sedimentary deposits that,
when free from moisture, still retain a certain ’degree of
firmness and cohesive power. My description of the
external characteristics of the samples refers chiefly to their
appearance when dry, in which state they were submitted
to analysis. I may observe here, that colour, mainly
dependent on the degree of oxidation, constitutes the most salient
distinctive feature of oceanic deposits.
Li the shallower parts of the sea along the coasts of
Norway and Spitzbergen we find the surface of the bottom
covered with a more or less plastic clay, almost invariably
grey in colour. The fineness of the substance composing
it and the admixture of coarser particles, such as sancl,
pebbles, calcareous shells, varies very considerably in the
numerous samples brought up from the sea-bed in those
localities. This coastal clay is rarely met with farther down
than 400—500 fathoms (700—900 metres).
At that depth the surface-layer of the bottom is
generally found to consist of a brown clay, which
announces transition to the true oceanic’deposit. Where it first
occurs, this brown clay, containing but few Foraniinifera
(transition clay), is often more or less sabulous and coarsely
granulated; but farther down it gets finer and more
homogeneous in sübstance, till it is ultimately merged into
that sedimentary deposit to which our naturalists have given
the name of •’Biloculina clay,’’ met with at almost all depths
exceeding 1000 fathoms.
Biloculina clay is a tine deposit varying in colour from
light to dark brown, and distinguished by a greater or less
abundance of minute Foraniinifera. Of those perceptible
to the naked eye,- by far the greater part belong to the
genus Biloculina, with its minute white shells, resembling
a pin’s head in size and shape, dispersed throughout the
sedimentary substance, to which these small animals give
a characteristic and easily recognisable appearance; —
whence the appropriate name suggested by the naturalists
to the Expedition.
We shall afterwards speak of the other Foraniinifera
that occur in this clay, but which, owing either to their
appearance or minute size, are less conspicuous than the
Biloculince, though greatly exceeding those animals in
number.
In the eastern tract of the Arctic ocean between
Spitzbergen, Beeren Eiland, and Novaja Zejlilja, we found
the bottom covered with a greenish-grey clay, containing
but few animal remains. Its green colour and other
distinctive features are particularly prominent in the samples
collected at the most easterly of the observing-stations.
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