16 THE CORAL REEFS OP THE MALDIVES. 



Line across the channel between Fadiffolu and Miladnmmadulu (PI. 8 a, 

 fig. 4). From Hurawali (Fadiffolu) to Karema (Miladummadulu). 



One mile north of Hurawali we found three hundred and forty-two 

 fathoms (No. 67), hard bottom. Four miles north, in the centre of the 

 channel, we obtained seven hundred and sixty-nine fathoms (No. 68). 

 One mile south of Karema we sounded in three hundred and forty fathoms 

 (No. 69). Unfortunately, no sample of the bottom of this channel was 

 obtained. No. 67 indicated a hard current-swept bottom. 



Line across Kardiva Channel, from Gaha Faro to Aligau (Fadiffolu) (PI. 8b, 

 fig. 11). 



One and a half miles north of Gaha Faro we sounded in two hundred 

 and forty-one fathoms (No. 51), and brought up a fragment of Oculina. Six 

 miles north of Gaha Faro, halfway to Karidu Island, we obtained two 

 hundred and fifty-eight fathoms (No. 52), with a hard bottom; and a mile 

 and a half sonth of Karidu we got two hundred and ninety-eight fathoms 

 (No. 53), bringing up coral sand and small fragments of Pteropod shells. 

 One mile north of Karidu we found three hundred and twelve fathoms 

 (No. 54), and brought up small pieces of pumice from a hard bottom. In 

 the centre of the channel between Karidu and Fadiffolu, seven and a half 

 miles north of Karidu Island, there seems to be a distinct ridge, as we 

 only obtained one hundred and ninety-seven fathoms (No. 55), with a bot- 

 tom of clean coarse Globigerinae sand. One and one-half miles south of 

 Aligau (Fadiffolu), we sounded in three hundred and seventy-two fathoms 

 (No. 56), with a bottom consisting of coarse coral sand and Globigerinae 

 sand. The edge of the Maldivian plateau drops gradually to the north of 

 Gaha Faro from two hundred and forty-one to three hundred and seventy- 

 two (Nos. 51, 56) near Fadiffolu. 



The northern part of the central basin is very open to the sea (PI. 1); 

 between Gaha Faro and Fadiffolu it slopes to the east, only a few higher 

 knolls, like Karidu, and the sounding of one hundred and ninety-seven 

 fathoms (No. 55) to the north, indicating its boundary. 



