The promised more on Janet Browne’s Darwin biography. A couple of sentences down on the same page (page 141, to be exact):
… Read the restAnd when Sedgwick arrived he tried to entertain him in an appropriately geological fashion by telling him of the gravel pits near Shrewsbury. But Darwin’s story of the labourer who found a tropical shell in the gravel brought only a peal of laughter and the remark that this could not be true. If the shell were genuinely embedded there, said Sedgwick, it would overthrow everything that was known about the superficial deposits of the Midland counties…Recounting the story later, Darwin remembered being astonished that Sedgwick was not more delighted by his strange fact. ‘Nothing before had ever made