I'd like to think that there comes a time in every Curator's life when they are left speechless by a donation. That time came for me a number of months
ago, caused by an unexpected and incredibly generous donation of some black smoker material. Black smokers are another name for hydrothermal vents from offshore volcanoes. In their natural environment they are surprisingly
common. But in Museum collections they are quite rare, which is why my jaw hit the floor when I opened their box that day.
As a geology curator at one of the UK's national museums, I had never set eyes on an actual black smoker, let alone had one in the collection I was responsible for. Ahhh, if only! I had only ever been impressed by documentary footage of them - chimneys on the ocean floor, spewing out vast quantities of thick, black, mineral-laden soup. So imagine my surprise when I opened an innocuous brown box one day last year, a donation from the Soregaroli family, a family with many years of close connection to the Museum. Could it be? Nooooo. No way! It is!! Seriously!!!......You get the picture!
Among geologists, black smokers hold an appeal and are quite coveted. They represent one of our remaining frontiers, the ocean floor. They talk to us of underwater volcanoes and plate tectonics, of metals such as gold and silver, and extreme environments in which incredible ecosystems thrive perhaps two kilometres beneath the ocean surface where the sun never shines and where the water spewing from the vents may reach 400oC. They are an environment that few of us will ever get to, but that many of us would no doubt love to experience.
Our black smokers came from the Axial Seamount (volcano) on the Juan de Fuca Ridge, off the coast of Oregon. Back in the 1980s, the Geological Survey of Canada, as well as other research institutions, led a series of research dives to explore and map the area. They were looking for hydrothermal vents and mineral deposits as well as discovering the life that thrived here. After all, the discovery of black smokers only came about in 1979 and so this was a new and fascinating area of science. The specimens that eventually have come to us were collected around this time. Many of them were collected on the Alvin, a famous submersible that has helped immensely in our exploration of the oceans.
What makes this donation even more important is its connection to Britannia's ore. Around 100 million years ago during the Cretaceous, this area was offshore in a shallow marine environment - a precursor to today's Juan de Fuca tectonics. Sedimentary rocks were being formed, interspersed with volcanic eruptions that laid down layers of lava and ash. Although the exact details for the formation of the ore here has never yet been fully agreed on, it is considered a Volcanic Massive Sulphide deposit which means that it was formed from offshore volcanic and hydrothermal related activity.
Although impressive, as specimens you can hold in the palm of your hand, our black smokers are small. So to round off this post, and to put them into perspective - and drive home their impressive nature - let's consider one of the biggest black smokers known - the Godzilla vent that also formed on the Juan de Fuca ridge. It measured around 150 feet in height before it partly toppled in the 1990s. The video below shows it in action. Who wouldn't want to go and visit there?!