Buried landscape?

Oil prospectors sonar-searching the sea bottom may have found an ancient landscape buried 2km below the seabed. Have a look at it yourself. The color scheme guides the eye--perhaps too much; I get a little suspicious when things look this good. But they've taken core samples and found pollen in the layer, which is suggestive. The story didn't say what the density difference was, or what was supposed to make the different rock textures show up. I'll have to get ahold of Nature Geoscience somehow.