46 0. B. B0GGILD. BOTTOM DEPOSITS. [norw. POL. EXP. 



In the first column are placed all the grains that did not consist of one 

 or a few recognisable individuals. Under this head come a number of 

 different minerals and rocks that cannot be very clearly distinguished from 

 one another. The greater part of the whole class is made up of iron con- 

 cretions, which, unlike those found among the heavier particles, cannot be 

 very strongly impregnated with iron. There is also every possible transition 

 to particles that consist exclusively of coagulated, hardened clay. The grains 

 in this column are to a smaller extent made up of fine-grained rocks such 

 as sandstone, porphery, etc. In the samples that contain particularly large 

 quantities in this column, by far the greater number are grey clayey particles, 

 e. g. No. 7, where the quantity is so great that the sand acquires a peculiarly 

 impure appearance. The proportion between the clayey matter and the other 

 mineral particles has been previously discussed as regards each separate 

 sample, and will not be further commented on. 



Respecting the proportion between felspar and quartz, the various 

 samples exhibit certain differences which may arise partly from the kind of 

 rock from which the sample had its origin, and partly from disintegration, 

 which will always greatly affect the felspar, and thus lower the percentage 

 in proportion to that of the quartz. The proportion of felspar is smallest 

 in No. 46, where the quantity is about ^ that of the quartz, and rises with 

 every possible transition to No. 9 where the proportion is 2 : 7. For the 

 rest it is impossible to say anything more definite as to the causes of these 

 variations, as long as nothing more definite is known about the geological 

 conditions in the places whence the samples come. 



The same may be said of the proportion between the various kinds of 

 felspar. On an average, about half of them are orthoclase. No. 6, however, 

 shows a remarkable exception to this, 7 out of 8 particles being orthoclase. 

 This sample must thus have originated from rocks that are essentially different 

 from the remainder. The quantity of plagioclase is always far below that 

 of the other kinds of feldspar, which corresponds with the general proportion 

 in granites and crystalline schists. 



