78 ON THE PEEP OCEANIC DEPEESSION 



On reference to my last year's Address it will be seen that the 

 " Challenger," when 30 miles from Kandavu, had a depth of 1,350 

 fathoms over red ooze. In the "Abstract" we find that the " Tus- 

 carora" had yellow brown ooze, at a depth of 1,647 fathoms, in a 

 position about 30 miles west from Kandavu. The observations 

 from the two ships are therefore so far connected. 



It is to be remarked, however, that in the "Tuscarora's" sound- 

 ings between the Eiji G-roup and New Caledonia, coraland 

 coral sand frequently occurred, and that the depths were very 

 unequal, only one reaching below 2,000 fathoms, whilst on 3rd 

 February, 1876, at a distance equivalent to 48 miles of latitude, 

 the soundings between the Isle of Pines and Queensland deep- 

 ened 668, from 715 to 1,383 fathoms, which would give a descend- 

 ing slope much steeper than that on our Western Railway line 

 from its highest point to the sea. Moreover, the depression deepens 

 again in a mean direction of N. 71 E. from Cape Moreton, in 

 Queensland, and, in 225 miles of distance, to a depth of more 

 than three vertical miles from the surface, and this within 95 

 miles from the Cape ; rising again in less than 60 miles to less 

 than three-quarters of a mile in depth in the same general 

 direction. 



This proves the existence of a very deep channel, not 100 miles 

 wide, commencing about 36 miles from Cape Moreton. Connect- 

 ing with the above calculation the " Challenger's" observations, 

 we learn that it does not extend far to the northward, since the 

 ridge from Sandy Cape to New Caledonia, &c., mentioned in my 

 " Notes," cuts it off at about 1,300 fathoms, which is nearly the 

 depth of the north-east slope at about 200 miles distance. This 

 deep channel would therefore appear to have a direction towards 

 that point of the compass. The absence of red clay and ooze from 

 the " Tuscarora's" soundings is curious, but it is in agreement 

 with the general depth assigned to deposits of that colour in the 

 " Challenger's " observations, which occurred below 2,500 fathoms, 

 and there are but three" Tuscarora" soundings between Kandavu 

 and Brisbane exceeding that depth, against which we read 

 "brown mud," " brown," and " yellow-brown," and " white," being 

 the only colours noted outside the Queensland coast de- 

 pression. It is, however, possible that colours may be variously 

 estimated by different observers, as one of the " Tuscarora's" bot- 

 tles contained what, to my eyes, appeared to have a reddish tint. 



Soundings brought up by H.M.S. " Herald" off Eiji, many 

 years ago, and supplied to me on board by Dr. Macdonald, E.R.S., 

 were filled ^\\th.foraminifera. The colour of the deposit now is a 

 light grey, after long drying in my cabinet. As white coral was 

 dredged by the " Tuscarora" only 320 miles N. 73 E. from Cape 



