2 Dr. Mac Culloch's Account ofCuemsey^ 



It will be seen that they are chiefly formed of granitic rocks. 

 The Inlands of Choze, which lie deeper in the Bay, are of similar 

 formation, and I am informed that Mont St. Michel is also a mass 

 of granite. Excepting this, I have not been able to obtain any 

 information with regard to the Coasts of Normandy or Brittany, 

 from the Islands of Brehat to La Hogue. But from the Seven 

 Islands to I'lsle de Siecle, including Morlaix and Treguier, I have 

 had opportunities of ascertaining that granite is the predominant 

 rock ; and more extensive observation may possibly prove, that a 

 chain of granitic rock extends from Cape La Hogue to Ushant , a 

 line parallel to that granitic chain, which runs in a WSW direction, 

 from Dartmoor to the Scilly Islands. This is rendered further pro- 

 bable, from the rockiness of the bottom of the sea, and the quartzose 

 gravel and sand which are brought up by the sounding line. 



The average depth of water in the neighbourhood of the islands 

 Is thirty-five fathoms ; it is scarcely any where more than forty, and 

 w^ith the exception of a few shoals, the bottom is tolerably uniform. 



Numerous rocks beset these coasts, some of which form large 

 chains lying in an east and west position. A variety of currents is the 

 consequence of the particular position of these islands in the Channel 

 stream, and the intricacy and rapidity of them, tend to form a very 

 difficult navigation, and a strong natural defence, to the islands. 



The tides on these shores rise to a considerable height, though 

 not nearly equal to their elevation in the bottom of the bay, where 

 the check to the Atlantic wave is greatest. The height which they 

 attain is from thirty to forty feet : at Guernsey it is thirty-two feet. 

 At St. Maloes it is said to exceed sixty. 



The great wave which enters from the Atlantic, striking directly 

 against the projecting Coast of Normandy, first fills the bay, and 

 then continues its course along the islands, and round La Hogue, up 



