20 RAMBLES OF A NATURALIST. 



Chausey is entirely granitic, and very probably 

 owed its existence to a special ebullition of that 

 great central fire whose fluid lava has contributed 

 to the formation of the thin crust which we in- 

 habit. When this incandescent mass issued from 

 the interior of the earth, it rapidly cooled. This 

 cooling process was followed by the sudden retreat 

 of the fluid masses, and this gave rise to intersecting 

 fissures which were soon filled with debris that have 

 produced the rotten stone. The latter is unable to 

 offer any prolonged resistance to the shock of the 

 waves ; and, by its disintegration, it isolates the 

 more compact blocks, which, notwithstanding their 

 enormous weight, are often transported to consider- 

 able distances by the force of the sea. During my 

 stay in the archipelago a section of rock, nearly 

 1000 tons in weight, was detached from the main 

 mass, and hurled to a distance of several yards 

 by the action of the waves, at a time when the 

 fishermen were able to pursue their ordinary daily 

 avocations. 



It would appear that the Chausey islands have 

 not always been as far removed from the continent 

 as they are at the present time. According to a 

 tradition which is universally diffused over the dis- 

 trict, this granitic mass once formed the head of a 

 dyke of rocks, protecting vast morasses and a con- 

 siderable forest, which is now submerged beneath 

 the waters. Some writers have even thought that 

 they were justified by ancient documents in referring 

 the probable date of this catastrophe to the year 709 

 of our era. Geological facts give a certain degree 



