89 



With regard to the mechanical constitution of the ingred- 

 ients \\hich the deposits get from moraines at the bottom of 

 the sea, it will be clear from what has been said that they 

 will be the coarser ones contained in the samples. All original 

 moraine-material is as a rule coarser than the material of 

 the samples, and from moraine-ridges where the currents are 

 strong part of the clay will always be washed away, so that 

 we must imagine such parts at the surface almost exclusively 

 covered by larger or smaller pebbles, and in the spaces between 

 them sand and clay will be found. If the sounding-tube rests 

 on one of the pebbles no sample will be taken up, but, as 

 a rule, we may suppose that it will be dragged some distance 

 along the bottom of the sea or, will of its own accord slide 

 down from the projecting pebbles. Such samples will be of 

 a very varying constitution, but are as a rule rather coarse. 

 The best proof of the fact that we have to do with mo- 

 raine-deposits is that, when we find a row' of coarser 

 deposits away from land, and others nearer land consider- 

 ably finer, such a difference can hardly be explained in any 

 other way. 



An examination of the nature of the pebbles which have 

 been taken up may tell us a great deal with regard to the pre- 

 sence of morainic material at the bottom of the sea. By look- 

 ing at the geological map we can draw fairly certain conclu- 

 sions as to what the constitution of the moraine-material will 

 be in each locality, and, in the places where the real facts 

 correspond with these conclusions we are somewhat justified in 

 supposing that the coarser ingredients of the samples were 

 derived from the moraine. As a rule, the moraine-material in 

 the samples now under discussion will be of a very mixed 

 nature, as each ice-current will have passed through several 

 different formations, but still there are some characteristic 

 features by which it can be distinguished from other material 



