 The isle of Jethou is around three @-@ quarters of a mile to the southwest beyond Point <unk> . It is possible that in AD 709 a storm washed away the strip of land that connected Jethou to Herm . About 215 metres ( 705 ft ) off the northern coast of Jethou is the islet of <unk> , which measures about 212 metres ( 696 ft ) by 168 metres ( 551 ft ) , with an area of less than three hectares . To the west , between Herm and Guernsey , lies the channel Little Roussel ( Petit <unk> ) ; between Herm and Sark , to the east , lies the Big Roussel ( Grand <unk> ) . <unk> Tower , a Victorian @-@ era fortification , is in the Little Roussel between Herm and St Peter Port . The tower was created by Thomas Charles de Putron ( 1806 – 1869 ) using granite from Herm between 1854 and 1856 . 
