55 



forskjellige Forhold, der endnu er os fuldkommen iibekjendte. 

 Vi har saaledes ingen Erfaring "in de kvantitative og tem- 

 porære Betingelser, der er givne for Grlobigerinernes Arlei- 

 ring paa Havbunden. Lige saa lidt kan vi af de i Bund- 

 prøverne fundne Skaller af ikke-pelagiske Foraminiferer 

 slutte os til. hvor stærkl de levende Dyr har været repræ- 

 senterede i Slammet, eller hvorlænge de døde Dyrs Skaller 

 vil uplievares paa Havbunden — tvende Spørgsmaal, der 

 vel niaa have sin Betydning for Slammets mekaniske Af- 

 leiring. Det er dog rimeligt at antage, at lang Tid kræves, 

 for at Søvandet skal kunne opløse disse Kalkskaller. Vi 

 ved af tidligere Forsøg, at de paaGrund af sin Gehalt paa 

 organiske Stutte ikke forholder sig som ren kulsur Kalk 

 ligeoverfor Opløsningsmidler, men at de angribes langt van- 

 skeligere. Man har fremsat den Paastand, at den kulsure 

 Kalk lettere opløses i Dybet paa Grund af ilen større 

 Mængde Kulsyre. sum her skulde tindes i Søvandet. Hr. 

 Tornøes Undersøgelser over Kulsyremængden i det af den 

 norske Expedition beseilede Hav modbeviser imidlertid denne 

 Antagelse. Han har fundet, at Søvandet overalt reagerer 

 alkalisk og altsaa ikke kan indeholde nogen fri. men blot 

 normalt- og surtbunden Kulsyre; Mængden af denne er 

 imidlertid paa Dybet omtrent den samme som ved Over- 

 dåden. At Forholdet skulde være anderledes i de øvrige 

 I >ele af Oceanet synes ikke at have nogen Sandsynlighed 

 for sig, naar man ser hen til de talrige Undersøgelser, der 

 stadfester Søvandets Ensartethed med Hensyn til dets 

 øvrige Bestanddele. Søvandets opløsende Evne ligeoverfor 

 den kulsure Kalk skyldes altsaa ikke dets Gehalt paa fri 

 Kulsvre. 



Den ovenomtalte Lagdannelse i Biloculinleret kan 

 ogsaa tænkes fremkommet ved en Slemningsproces, hvis 

 Våndets Strømninger paa Bunden er stærke nok til at 

 sætte Slammets fine Partikler i Bevægelse. Dette Spørgs- 

 maal er imidlertid lige saa ubesvaret som de foregaaende. 

 Det fortjener imidlertid at nævnes, at alle de fra Bunden 

 optagne Vandprøver altid var ganske klare og uden Spor 

 af svævende Partikler. 



Betrågter vi paa Kartet den ostlige Grændselinie for 

 Biloculinleret. vil vi tinde, at den i Almindelighed gaar 

 imellem 900 og 1100 Favne. Imidlertid træffer vi dog paa 

 flere Steder Biloculinleret paa mindre Dyb, ligesom det 

 ogsaa hænder, at det først begynder at vise sig under 1 100 

 Favne. Mellem G-t" 'og 08° N. B. gaar Biloculinlerets 

 vestlige Grændse op til et grundere Dyb end længere Nord. 

 Paa Stationerne 54. 96 og 248 møder vi det saaledes alle- 

 rede paa 600. 805 og 778 Favne. Udenom den sidstnævnte 

 Station, der ligger omtrent 50 Mile fra Laiid, gjør Dybde- 

 kurverne for 800 — 1000 Favne en skarp Beining (sml. Side 

 40) indover mod Kysten indtil en Afstand fra denne af ca. 

 oO Mile; paa denne Strækning ligger Græudsen for Bilo- 

 culinleret imellem 700 og 800 Favne. Paa den- brat skraa- 

 nendé Havbund udenfor Lofoten og Vesteraalen tinder vi 



an intimatc acquaintance with divers conditions as vet 

 wholly unknown. Thus, for instance, we have everything 

 to learn réspecting the causes that determine the quantita- 



tive and tempnrary distrihution of GlobigerinCB over the 

 sea-bed. Nor can we from the proportion of non-pelagic 

 foraminiferous shells inter bow numerously the living ani- 

 mals were represented in the deposit or the length of the 

 period during which their shells are preserved from decom- 

 position at the bottom of the sea — questions which cannot 

 but. exert considerable influence when investigating the me- 

 chanical conditions that determine the character and extent 

 of the deposit. One thing is however tolerably certain, 

 that a long time must elapse ere the sea-water can dissolve 

 those calcareous shells. As shown by experiment, they 

 differ trom pure carbonate of lime in yieldjng much more 

 slowly to the action of solvents, by reason of their large 

 proportion of organic substances. Some are disposed to 

 maintain .that carbonate of lime is more readily soluble in 

 the depths of the ocean owing to the greater ainount oi 

 carbonic acid which the water has been held to contain 

 there. Mr. Tornøe, however. in his Memoir on the car- 

 bonic acid in the Seas explored by the Norwegian Expedi- 

 tion. has. I think. successfully refuted that assumption. 

 Sea-water he invariably found to react as an alkali ; and 

 hence its carbonic acid cannot occur free, hut must ob- 

 viously be combined with oxygen; as regards the proportion 

 of that constituent. it is about the same in the depths as 

 at the surface, and the general uniformity in composition 

 shown by numerous investigations to characterize sea-water. 

 precludes the probability of any deviation in this respect 

 occurring throughout the intermediate strata. The power 

 possessed by sea-water of dissolving carbonate of lime can- 

 not therefore lie in a greater or less proportion of free 

 carbonic acid. 



The exceptional formation mentioned above as distin- 

 guishing Biloculina clay in some localities. might also be 

 ascribed to the action of bottom-civrrents. if sufticient to 

 intermingle and keep in motion the tine particles of the 

 deposit. But this, like the foregoing, is a question which 

 for the present we cannot pretend to decide. Meanwhile, 

 all samples of water brought up from the bottom were per- 

 fectly clear, without a trace of floating particles. 



( )n referring to the map ahnexed to this Memoir, 

 the eastern limit of Biloculina clay will be seen to lie at 

 a depth ranging from 900 to 1100 fathoms. In several 

 localities however Biloculina clay is met with nearer the 

 surface, and on the other hand, in some places it does not 

 begin to occur till the depth has reached 1 lex» fathoms. 

 Between lat. 64° and 68° N.. the western limit of the 

 Biloculina clay extends over a shallower part of the sea- 

 bed than farther north. Thus. for instance. at Stations 54. 

 96. and 248 it lies at a depth of 600. 805, and 778 

 fathoms. Without the last of these Stations (about 50 

 geographical miles from land), the curves of depth for 800 

 to 1000 fathoms (see page 40) make a sudden bend in the 

 direction of the coast. which they approach within a distance 

 of 30 geographical miles, and throughout this tract the 



