Darwin eagerly looked forward to seeing newly formed volcanic islands and took every opportunity to go ashore while "Beagle" was methodically moved round to chart the coast. He found broken black rocky volcanic lava scorching under the hot sun, and made detailed geological notes of features including volcanic cones like chimneys which reminded him of the iron foundries of industrial Staffordshire. He was disappointed that he did not see active volcanoes or find strata showing uplift as he had hoped, though one of the officers found broken oyster-shells high above the sea on one of the islands. Abundant giant Galápagos tortoises appeared to him almost antediluvian, and large black marine iguanas seemed "most disgusting, clumsy Lizards" well suited to their habitat – he noted that someone had called them "imps of darkness". Darwin had learnt from Henslow about studying the geographical distribution of species, and particularly of linked species on oceanic islands and nearby continents, so he endeavoured to collect plants in flower. He found widespread "wretched-looking" thin scrub thickets of only ten species and very few insects. Birds were remarkably unafraid of humans, and in his first field note, he recorded that a mockingbird was similar to those he had seen on the continent.