The first geo-dive went ahead from yesterday into today and the mission was simple. Collect as many different types of rock as possible! We want to really understand the geology of the area and in order to do that we need rocks. But there is a problem - under the sea all rocks look the same. They are dark, blocky looking, often covered in biology and sediment, and often too large to pick up with the robotic claws. However, occasionally luck is on our side and something unusual catches our eyes.
Mysterious purple rock near a vent
This is a picture of a mysterious purple rock taken near hydrothermal venting. By chance, a fresh face has been revealed and we can see an unusual veiny purple interior. Under the water we can only guess at what this is, and often our guesses turn out to be badly wrong, but once we get this sample up on deck we can have a proper look. Other rocks we have seen so far have varied greatly in their composition. We've collected peridoties, which originate in the mantle, gabbro, which forms the lower part of oceanic crust, and basalt, which forms the upper part of the oceanic crust. Together, these rocks represent a section through the crust and will help us understand the setting and chemistry of the hydrothermal venting.
By Alex Webber.
The action in the ROV van during the Isis Geo-dive 199