THE SUNKEN LAND OF BUS. — POOLE. 195 



In addition to the accurate location of the soundings marked 

 on the chart, information derived from other observations was 

 also kindly supplied, and this may be thus summarized f — 



Currents : An undercurrent constantly setting to the south- 

 west at a rate of about half a mile an hour, was determined by 

 the buoys which moved in that direction regardless of the sur- 

 face How and the wind. 



Deposits : The sounding tube and the mushroom anchors 

 brought up samples of various sorts of deposits, some that 

 adhered to the anchor like mud, are so noted on the chart ; 

 others were of fine or coarse sand with, in some cases, small 

 dark coloured stones. Then there was ooze and small shells. 



Blue mud : This name was given to a deposit which, when 

 freshly obtained, had a decided blue tint that it lost after 

 exposure for some time in the air. The blue layer underlaid one 

 of a yellowish cast and was alone obtained by tlie mushroom 

 anchors. The sounding tubes did not penetrate deep enough 

 to reach it. The tint doubtless was due to iron passing from 

 the ferrous to the ferric oxide. In two localities the deposit 

 was found to yield manganese, but in what form I am not able 

 to report, as the samples were transmitted to London. The 

 presence of the allied metals, iron and manganese, with a 

 growing calcareous deposit, has its interest for students of the 

 metalliferous zone of the Lower Carboniferous rocks of Nova 

 Scotia, in which occur in irregular masses deposits of both 

 iron and manganese. 



Sand : This, so far as I am aware, was not the product of 

 quartz, but of the breaking down of the siliceous and calcareous 

 casings of organisms. 



Pebbles : Of these a few were obtained in the sounding- 

 tube. Their composition has not been examined, but their sur- 

 face is smooth to the touch and pitted by erosion. In addition 

 to these were fragments as large as the tube would bring up, of 

 volcanic glass showing the usual conchoidal fracture, and mixed 

 with the ooze were small grains of volcanic ash. 



Pkoc. & Trans. N. S Inst, Sci., Vol. XI. Trans,— N. 



