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5
..Rhabdammina-Ler" efter en Foraminifer. som ofte
forekommer paa denne Del af Havbunden.
Rundt omkring den vulkanske 0 Jan Mayen bestaar
Bundens Aflejringer af et graasort fint Sand eller Sandler,
der indeholder talrige Brudstykker af den basaltiske Lavas
Mineraler.
Expeditionen Dybdemaalinger langs Islands Østkyst
viste, at Bunden her var af en noget uligeartet
Beskaffenhed. Selv paa de større Dvb (indtil 844 Favne) stødte
Loddet flere Gange mod Sten og kom op uden nogen
Bundprøve. Ved de nordlige Stationer paa denne Rute fandtes
et mørkgraat Ler. paa de sydlige syntes Sand og Sten at
være fremherskende.
Efter disse foreløbige Meddelelser vil jeg nu give en
ordnet Fortegnelse over det foreliggende Materiale, i
hvilken man vil finde en kortfattet Beskrivelse af
Bundprøvernes Udseende og Art. Hvacl der i det foregaaende er sagt
om Slamarternes Udbredelse belyses nøiere af det vedføiede
Kart. som i clet følgende skal nærmere forklares
Slam-arterne er paa dette Kart betegnet hver med sin naturlige
Farre. Forat faa disse i. Overensstemmelse med
Virkeligheden har jeg ladet dem kopiere efter et Originalkart,
malet med pulveriserede Bundprøver, udrørte i Gummivand.
De Stene, der fandtes i Bundprøverne, hvilke ligeledes
er medtaget i’følgende Fortegnelse, kunde naturligvis blot
være af en ringe Størrelse. Hvor der paa Havbunden laa
Stene, der var større end Aabningen af Jernrøret, hvormed
Bundprøverne optoges, maatte dette ialmindeliglied komme
tomt op. og i Loddejournalen noteredes i saadanne Tilfælde:
haard Bund, eller: Fjeld. Den sidste Benævnelse er dog
ved senere Overveielse blevet afskaffet, da den lettelig kan
lede til en Begrebsforvirring, forsaavidt som den fører
Tanken hen paa større sammenhængende Stenmasser, hvis
Nærværelse naturligvis ikke kan bevises derved, at
Jernrøret kommer tomt op. Jeg har i dette Tilfælde benyttet
Udtrykket: Stenbund.
De fleste af de Bundprøver, der er optagne paa
Kystbankerne indenfor det graa Lers Omraade, indeholder Stene
i vexlende Mængde og af forskjellig Størrelse. Mangengang
udgjorde disse en væsentlig Del af Bundprøven, saaat denne
i tørret Tilstand lignede et Konglomerat.
I Bundprøverne fra Biloculinleret fandtes ogsaa af
og til enkelte Stene, især i den nordlige Del af Havet.
De større Stene, der optoges med Skraben eller
Trawlen. blev ialmindeliglied bestemte ombord af Hr. Professor
Mohn. der velvillig har overladt mig sine Optegnelser; en
Del blev først efter Hjemkomsten undersøgt.
Jeg vil her -paa Forhaand gjøre opmærksom paa, at
This deposit our naturalists have termed "ühabdammina
Clay," after a genus of Foraminifera which often abounds
in that part of the ocean-bed.
Oft’ the volcanic island of Jan Mayen, the
surface-layer of the bottom consists of a tine, dark-grey sand, or
sabuloüs clay, containing numerous particles of basaltic lava.
The soundings taken along the east coast of Iceland
show the bottom to be somewhat variable in character
throughout that locality. Even in the greater depths (as
far down as 844 fathoms, for instance) the leaa repeatedly
struck against rock or stone, and cnrae up with the tube
empty. At the northern Stations in this tract we found a
bottom of dark-grey clay, whereas at the southern, sand
arid stone would seem to predominate.
I will now, after the above preliminary observations,
give a List of the samples collected on the North-Atlantic
Expedition, along with a brief description of their nature
and appearance. What has already been stated concerning
the distribution of the oceanic deposits. treated of in this
Memoir, the accompanying map. of which a detailed
explanation will afterwards be given, more fully elucidates. In
this Map each section has the colour actually distinguishing
the deposit it represents. That the different colours might
be as true as possible to nature, I had them copied from
an original map coloured with pulverized samples of the
bottom dissolved in gum-water.
The pebbles found in the samples of the bottom
aud included in the following List, could .be naturally
but of- trifling magnitude. If, in the locality where a
sounding was taken, the sea-bed was covered with stones
larger than the opening of the iron tube with which the
samples of the bottom were collected, the apparatus would
as a general rule come up empty, in which case "hard
bottom" or "rock" was entered in the sounding-journal.
The term rock, however. I have seen fit, after mature
consideration. to reject, since it might very naturally give rise
to misunderstanding, and be taken to signify a connected
mass of stone, whose existence there is of course nothing
whatever to prove in the fact of the tube coming up
-without a sample of the bottom. The expression "bottom stony"
is therefore substituted for "rock", as less liable to
misconstruction.
Most of the samjiles collected on the coastal banks,
where a grey clay predominates, contained pebbles varying
in number and magnitude. Frequently indeed they
constituted the principal part of the sample, which, when dry,
resembled conglomerate in appearance.
A few pebbles occurred too in the samples of
Bilo-culiiia clay, more especially those from the northern part
of the ocean-tract explored.
The larger stones brotight up in the dredge or trawl
were as a rule determined on board by Professor Mohn,
who has kindly placed his memoranda at my service: some
few however were not examined till after the return of the
Expedition.
With regard to’ my determination of the pebbles
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