he wondered why deep-ocean plankton had been created with so much beauty for little purpose as no one could see them. He saw landforms as supporting Lyell's Uniformitarianism which explained features as the outcome of a gradual process over huge periods of time, and quickly showed a gift for theorising about the geology he was examining. He concluded that the land had indeed risen, and referred to loose rock deposits as "part of the long disputed Diluvium". Around 1825 both Lyell and Sedgwick had supported William Buckland's Catastrophism which postulated diluvialism to reconcile findings with the Biblical account of Noah's ark, but by 1830 evidence had shown them that the "diluvium" had come from a series of local processes. They still distinguished between diluvial and alluvial deposits, but Sedgwick no longer thought these deposits were connected with Noah's flood by the time he taught Darwin, though the debate continued. Darwin's notes show him increasingly discounting "debacles" to account for such formations. It was only later that glaciation was accepted as the source of these deposits. Lyell's second volume explained extinctions as a "succession of deaths" due to changed circumstances with new species then being created, but Darwin found giant fossils of extinct mammals with no geological signs of a "diluvial debacle" or environmental change, and so rejected Lyell's explanation in favour of Giovanni Battista Brocchi's idea that species had somehow aged and died out. On the Galápagos Islands he remained convinced by Lyell's idea of species spreading from "centres of creation", and assumed that species had spread from the mainland rather than originating on these geologically recent volcanic islands. He failed to note locations of most of his finds, but fortunately recorded mockingbirds and plant life with more care. In Australia, reflecting on the marsupial kangaroos and potoroos, he thought them so strange that an unbeliever "might exclaim 'Surely two distinct Creators must have been [at] work; their object however has been the same & certainly the end in each case is complete'", yet an antlion he was watching was very similar to its European counterpart. "Now what would the Disbeliever say to this? Would any two workmen ever hit on so beautiful, so simple & yet so artificial a contrivance? It cannot be thought so. – The one hand has surely worked throughout the universe. A Geologist perhaps would suggest, that the periods of Creation have been distinct &