THE DEPOSITS OF THE SEA-BOTTOM. 



13 



The small amount of minerals must be caused either by an uncommonly small transport of solid 

 ingredients from the continents into the surrounding seas, a fact that can only be supposed to have 

 been caused by the climate being at the same time as well warm and dry to prevent the formation 

 of larger rivers as specially calm, that the beating of the waves might not erode at the shores and 

 the currents carry the material into the sea. Or else the deposition of Foraminifera and the still 

 smaller calcareous organisms must have been uncommonly abundant in that time, wich may perhaps 

 also be supposed to be a consequence of a specially warm and calm climate. As especially the Fora- 

 minifera living on the sea-bottom, play a proportionally prominent part in the chalk, while in the 

 Globigerina clay they are only found in small numbers in proportion to the Globigerina, the circum- 

 stances on the sea-bottom may be supposed to have been especially favourable to the Foraminifera 

 and the other calcareous organisms, possibly also on account of higher temperatures. The depth on 

 which the chalk has been deposited, can, on account of the land being so near, scarcely be supposed 

 to have been so great as that on which the Globigerina clay is formed; neither is it likely that in so 

 many places of the earth as where the chalk now is found, so enormous upheavals should have taken 

 place, as would have to be supposed, if the chalk had originally been deposited on the depth of 

 1 — 3000 faths where the Globigerina clay is now found. 



Having thus given an account of the distribution of the different sorts of deep-sea deposits in 

 the territory navigated by the Ingolf Expedition, and of the most prominent facts regarding their 

 nature, it may perhaps be thought appropriate here to try to account for some of the factors that 

 have been cooperating in the deposition of these sediments, and have been the conditions of their 

 distribution on the sea-bottom. On account of the large number of these concurrent factors it is, 

 however, only possible in a comparatively small degree to account for the influence of each among 

 them. In most instances the collection of specimens I have had at my disposal, has not given 

 sufficient information so as to enable me to account for the facts that moreover in the territory 

 explored by the Ingolf Expedition are especially intricate; from certain regions of the territory speci- 

 mens are wanting exactly on places where they are most missed for the explanation of some pheno- 

 menon, while in other places only a single specimen has been taken, from which it will not do to 

 draw more general conclusions, as the casual irregularities that may take place, are sometimes rather 

 large; two specimens taken close to each other, will often show very essential differences in one or 

 more directions, so that only a comparison with more adjacent specimens has made it possible to 

 decide for each single case, what was the rule, and what the exception. 



What I intend to examine in the present section, is the amount of lime, this quality being, 

 as before mentioned, the most essential and most characteristic of the species of the specimen. The 

 quantity of carbonate of lime in a specimen is chiefly dependent on two large groups of factors viz. 

 partly such as cause a greater or smaller supply and distribution of material from the land, and partly 

 such as may influence the deposition of greater or smaller numbers of organisms with calcareous 

 shells. As to the supply from land, it will be immediately evident that the extent of the country 

 must largely influence the mass of material carried away from it; by regarding the chart, plate II, it 

 will also be seen that the curves are gathered especially closely round Jan Mayen and the Faroe 



