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49
det — rigtignok enestaaende — Tilfælde, i hvilket jeg har
päavist en Oxydation af Bundprøven ved dens Henliggen i
Luften. En saadan Forandring skulde altsaa foregaa med
stor Langsomhed i Havet.
.Teg vil imidlertid langtfra paastaa, at den ovenstaaende
Forklaring er den rigtige; jeg indrømmer, at den staar
paa meget svage Fødder, og har derfor blot fremsat den
som en Gisning, for at henlede Opmærksomheden paa
Slamarternes eiendommelige Oxydationsforhold. Talrige andre
Omstændigheder maa ogsaa tages i Betragtning ved
Afgjø-relsen af dette Spørgsmaal. Saaledes er det f. Ex.
utvivlsomt. at de i Slammet forekommende Dyr bidrager til dets
Oxydation. Især finder man ofte en Udskillelse af rødt
Jernoxyd paa de Punkter af Leret, hvor Annelider har
gravet sig Gange. Mange Foraminiferer virker i den samme
Retning, idet de danner sig stærkt jernoxydholdige Skaller.
Som forud omtalt er Rhabdammina-Leret meget fattigt paa
Dyrelevninger.
En af de Stene, der blev fundne i Østhavet paa Ståt.
267, har jeg nærmere undersøgt. Det var en finkornig,
blaagraa Sandsten med stærkt kalkholdigt Bindemiddel
(Kalksandsten). I det saltsure Udtræk af denne Sten —
tilberedt paa samme Maade som i Bundprøverne — fandtes:
1.38 pCt. FeO og 0.59 pCt. Fe20.5.
Altsaa et lignende Forhold som i Rhabdammina-Leret.
I Overensstemmelse med hvad der er sagt under
Beskrivelsen af det graa Ler, vil det være indlysende, at vi
ikke med Nøiagtighed kan bestemme Rhabdammina-Lerets
sydlige og vestlige Grændser, da vi mangler de nødvendige
Observationer fra-denne Del af Havet. Den sidste
hollandske Expedition i 1878 har foretaget endel Dybdemaalinger
i Retningen Vardø ^Beeren Eiland. men Bundens
Beskaffenhed er ved denne Anleduing ikke blevet nærmere undersøgt.
De paa Side 40 omtalte uregelmæssige Atieiringer af
brunt Sand og Sandler. der forekommer i Syd og Sydvest
for Beeren Eiland. kan maaske ogsaa med Hensyn til sin
Dannelse staa i Forbindelse med denne 0.
been lying at the bottom of the sea. Nay. this view will
appear still more plausible if we call to mind the case —
isolated, it is true — in which I succeeded in determining
the oxidation of oceanic deposit after exposure to
atmospheric influence. This change in chemical composition
must accordingly be very slow on the sea-bed.
Meanwhile. I would by no means venture to imply,
that the above explanation is correct; it has weak
points, I freely admit, and has therefore been advanced
suggestively, with the object of drawing attention to the
characteristic results of oxidation in the various deposits.
Many other conditions must be taken into account ere this
question can be decided. Thus, for instance, the living
organisms that occur in the deposit contribute beyond a doubt
in some measure to its oxidation. In particular, red oxide
of iron is frequently found deposited on the clay where
Annelids have excavated their passages; and numerous
species of Foraminifera operate with a like result, their shells
being rich in oxide of iron. As previously stated.
Rhabdammina clay contains very few animal remains.
One of the mineral fragments brought up in the East
Sea. at Station 267. I have submitted to analysis. It was
a piece of finely granulated, bluish-grey sandstone, with a
large admixture of cemeutitious lime (calcareous sandstone).
In the hydrochloric acid decoction of this mineral substauce
— prepared precisely as was that for analysing the samples
of the bottom — I determined: —
1.38 per cent of FeO and 0.59 per cent of Fe^Oa.
accordingly the same proportion as in Rhabdammina clay.
From what has been stated in the description of the
green clay, it is obviously impossible to define with
accuracy the southern and western limits of the Rhabdammina
clay,’ the necessary observations not having been taken in
that part of the North Atlantic. The last Dutch
Expedition. however, took a series of soundings between Vardø
and Beeren Eiland. but those explorers did not pay any
particular attention to the nature of the sea-bed.
The exceptional surface-layers of brown sand and
sabulous clay mentioned on page 40. and occurring south
and south-west of Beereu Eiland, may possibly as regards
their formation be connected with that island.
Brunt Ler.
(Overgangsier og Biloculinler i.
Ved Dybder, "der er større end 500 Favne, finder
man i Almindelighed Bunden bedækket af et bruntfarvet
Sediment. Dette er i Begyndelsen af sin Optræden mindre
fint og ensartet (sandholdigt) og af en mere graalig Farve
end længere ud i Havet, hvor Biloculinerne forekommer.
De Grændser, indenfor hvilke disse Foraminiferer med
Regelmæssighed og i større Antal optræder, ligger i
Almindelighed et godt Stykke indenfor det brune Lers egentlige
Omraade. Den mere eller mindre brede Strimmel af brunt
Den norske Nordhavsexpeditiou Schmelck: Chemi.
Brown Clay.
(Transition Clay and Biloculina Clav.)
At depths exceeding 500 fathoms, a brown-coloured
clay is generally found to constitute the surface-layer of
the bottom. Where it first occurs, this deposit is
coarser and less homogeneous in substance (sabulous),
and of a greyer shade than farther from the coast,
where its chief characteristic consists in the presence of
Bilocidinæ. The limits for the occurrence of these
Foraminifera as a constant feature and in greater numbers,
reach as a rule a good distance within the true province
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