l(, THE DEPOSITS OF THE SEA-BOTTOM. 



where the bottom is covered with a Gray deep-sea clay very poor in lime though according to the 

 position we should expect to find Transition clay or Globigerina clay; in what manner the ridge is 

 able to get such an influence is not quite clear; as the specimens found on it, are as rich in clay as 

 most of the others, the circumstances must also be favourable to the deposition of the finer calcareous 

 organisms; but perhaps the circumstance may here be of some importance that the currents running 

 along both the northern and southern coast of Iceland, meet here, and run together eastward towards 

 the Faroe Islands, so that the material from Iceland gets a specially good opportunity for spreading 

 in this direction; possibly a factor may also here be of some importance, which we have not hitherto 

 taken into consideration, viz. the circumstance that firm rocks on the bottom may produce part of the 

 loose material found in the bottom-specimens. We must especially expect this circumstance to be of 

 importance on a ridge like the mentioned, which is not everywhere covered with loose soil, but 

 partly consists of firm rocks that may even be rather rugged. 



According to Delesse submarine rocks are almost always found outside a rocky coast, and 

 they may by erosion and disintegration give rise to the formation of loose layers in the hollows 

 between them. Delesse likewise mentions the fact that on the edge between Iceland and the Faroe 

 Islands numerous such rocks are found even to a depth of 600 metres. Whether such firm rocks may 

 be subject to any breaking down on the bottom of the sea is a question that cannot be directly 

 examined; it may be taken for granted, that the bursting caused by the frost, cannot assert itself no 

 more than the influence of the roots of plants, and also the mechanic erosion must be of small 

 importance, the sea water being almost quite free of firm ingredients, and the moving being on deeper 

 water rather slight. Thus the only agent able to corrode the rocks, is the disintegration; as the sea- 

 water always contains some carbonic acid, there is a possibility of the feldspars being transformed into 

 kaoline, and also of the disintegration of the other silicates; as the rock is never homogenous, some 

 parts will decay, while others remain more or less unchanged, and thus the rock will be transformed 

 partly to clay, partly to sand or gravel with all sizes of grains. Now as the currents are rather weak 

 on the ridge, and the beating of the waves has no influence so far down, the formed material must 

 be distributed in such a manner that the coarser parts remain on the spot itself, or, if this be elevated 

 in proportion to the surroundings, are only carried a little way off, while the finer parts, and espe- 

 cially the clayey particles, may partly be carried to a greater distance before precipitating; perhaps 

 they may also be redeposited several times, if the currents at times get another direction than the 

 common one, there being then no shelter on the same places as before. The result of it all will be 

 the formation of deposits of rather different habits; some will be tolerably pure clay, while others will 

 be shaped as boulder-clay and contain every possible size of grains. As the latter habit is predomi- 

 nant in the specimens taken on the ridge, it may be taken as a sign of the ridge consisting of rather 

 rugged, firm rock; in a later section, in which the mineralogical nature of the specimens will be 

 examined more closely, it will be shown that some of the coarser ingredients show signs of having 

 been produced in the immediate vicinity of the specimen, while others must be taken to have been 

 brought sometimes even from a very great distance, which can scarcely have taken place by other 

 means than the ice. 



In the other localities the nature of the bottom -specimens does not so decidedly suggest the 



