The contrast couldn’t be larger: after sampling varves in a forested river estuary, we are now drilling the deepest basin in the Baltic Sea: the Landsort Deep. With its water depth of 459 meters, there is a large distance to bridge with pipe before the drillers reach the sediment.
This is an extremely interesting site for microbiologists and geochemists because of its unusual characteristics: the deeper water is completely devoid of oxygen and is instead rich in - highly toxic - hydrogen sulfide. The marine surface sediments here are black and extremely wet, soft and smelly.
The sediment is full of methane gas. Drilling holes in the core liner comes with a risk….
The mud may squirt into your face!
Below the black mud, we’ve found more greyish-green clayey sediments from the time when the Baltic Sea was a lake. Drilling continues steadily, despite somewhat rougher weather conditions.