"Beagle" and "Adventure" now surveyed the Straits of Magellan before sailing north up the west coast, reaching Chiloé Island in the wet and heavily wooded Chiloé Archipelago on 28 June 1834. They then spent the next six months surveying the coast and islands southwards. On Chiloé, Darwin found fragments of black lignite and petrified wood, at least two of which the British Geological Survey discovered in 2011 locked away in their collection labelled "unregistered fossil plants". Exchanged with Joseph Dalton Hooker about ten years later, one slide was signed "Chiloe, C. Darwin Esq".