The first investigations of St. Helena geology were made when Charles Darwin visited the island on the voyage of H.M.S. Beagle in July 1836. He "used the observations on St Helena to formulate an intermediate hypothesis (published in 1844 in his book "Geological Observations on the volcanic islands and parts of South America visited during the Voyage of H.M.S. "Beagle") - volcanoes rise by slow, gradual and episodic events".[1]