Marine Muds and Nodules 135 



dredging in the summers of several years (1877-1882) in the 

 seas on the west coast of Scotland, and on the 2ist September 

 1878 I brought up from the deepest parts of Loch Fyne (104 

 fathoms) a quantity of sandy mud, with large quantities of 

 dead pecten shells, and along with them true manganese 

 nodules, with all the outward characteristics of those from 

 the greatest depths of the open ocean; and this similarity 

 was maintained on chemical examination. The dredging 

 anchor must on this occasion have been dropped in the very 

 richest part of the deposit ; for the mud, which had under- 

 gone no concentrating process, was found, on being submitted 

 to mechanical analysis, to consist of rather over 30 per cent, 

 of nodules 1 . This was a very remarkable discovery; for 

 although peroxide of manganese was not wanting in the 

 shallower dredgings of the "Challenger," it existed only as 

 coatings and similar deposits and not as nodules, which were 

 believed to be dependent for their formation on the conditions 

 obtaining in very deep water. After this, particular attention 

 was paid to the occurrence of manganese in all dredgings, 

 and it was found to be abundant all round our coasts as a 

 im on slu-lls, and more especially as the binding and 

 colouring matter of worm tubes; but no nodules were any- 

 where found except in the deep part of Loch Fyne. Some 

 years afterwards Mr Murray found them in great abundance 

 on the Skelmorlie Bank in the Firth of Clyde in 10 fathoms. 



In the same summer (1878) I made a number of ob- 

 tions in nnel off the north-east part of tin- Island of 



n, whnv tin water reaches a depth of 90 fathoms. A gal- 

 sed iron bucket was used as dredge, with a \\vight attached 

 nd, and one before it; so that n was rather to 



-kirn the surface than to dii; into tin 1, 



It brought up a quantity of a very fine red mud, in \\hi< h 

 i^anese grains could be detected, not apparently differing 

 from those found in oceanic rrd < lav^ In the process of 

 levigation, win -n tin- mud was stirred up \\ith wat< r and the 

 >n poured off. 1 MT portion \\hith 



to the bottom of the vessel had the appear 

 >r, 1878, voL xvm. p. 628. 



