Darwin wrote "A most remarkable conglomerate, consisting of mashed bits of porphyritic, jaspery, volcanic rocks, partly embedded in a ferrugineous base, but the whole mixed with patches & thin layers of pitchstone, passing into the nature of obsidian. I should think has certainly flowed as a lava with obsidian. Base of Central Hills. (The glassy rock is some igneous rock allied to the obsidian, partially decomposed, the obsidian greenish black: a concretionary pisolitic structure)"
Collected in July 1836.
This collection was a collaboration between The Open University and the Sedgwick Museum, created in 2009 to celebrate the bicentennial of the birth of Charles Darwin.
The Sedgwick Museum opened a new gallery, 'Darwin the Geologist', and created a museum-based virtual microscope to showcase rocks he collected during the Voyage of the Beagle. We enjoy this collection because Darwin did not always pick up a representative sample from the islands he visited; it's often the unusual rocks that caught his eye. Just explore the collection and you'll see what we mean. For those who have the opportunity, a visit to the museum is strongly recommended.