CANNA, GENERAL DESCRIPTION. 445 



CANNA.* 



THIS island presents, both in its general aspect and 

 geological structure., characters of such frequent occur- 

 rence among the Trap isles, that, unless it be among the 

 first to be examined, it scarcely offers any thing either to 

 detain or interest a geologist. Its similarity to the north- 

 western part of Sky in particular is such, that they 

 almost seem to be portions of the same general mass. 



Canna is four miles and a half in length and one in 

 breadth ; presenting on the south side an irregular decli- 

 vity descending by a succession of terraced steps to the 

 shore ; while nearly the whole northern side is bounded 

 by vertical cliffs terminating in the usual slope which 

 accompanies the rocks of trap. Its height is estimated 

 at 800 feet, the land being highest toward the west end, 

 and subsiding about the middle into a flattish neck which 

 rises again into a similar terraced hill at the eastern extre- 

 mity. It is accompanied by a kind of subsidiary island 

 called Sandy island, to be afterwards described, united 

 to it at low water by a long reef of rocks terminating 

 in a small sandy bay. The occurrence of sand on a 

 basaltic shore leads the geologist at first to suspect the 

 existence of secondary strata; but these suspicions are 

 immediately removed on examining the quality of the 

 sand, which is found to consist solely of pulverized 

 shells. 



The surface of Canna is almost entirely covered with 

 fine grasses ; a little heath, and that of stinted growth, 

 being found on the tops of the hills. A few undrained 



* Kanin, a rabbit, Swedish ; the isle of rabbits. No particular map 

 of this island being required, the reader is referred to the general one for 

 its position. 



