About the Cover

The front cover shows a multibeam swath bathymetry image of Rosemary Bank, an underwater seamount in the northern Rockall Trough 230 km NW of the Butt of Lewis. The apparent illumination in this image is from directly overhead. The seamount is approximately 60 km in diameter and measures over 1800 m from the floor of the surrounding bathymetric moat to its summit. The highest point, a volcanic pinnacle, is still more than 300 m below sea level.

The image shows irregular lava fronts, especially in the north and west, pinnacles from ?late-stage eruptive events, and a central, sub-circular dome. A veneer of Eocene sediments occurs on the SE of the summit plateau. The bulk of the seamount probably comprises basaltic lavas although more exotic igneous lithologies, such as highly-potassic lavas and tuffs, have also been recovered.

The age of the seamount is debated and its formation may have been episodic, possibly starting in the Late Cretaceous and extending into the Eocene. Magnetic data show that both normally and reversely magnetised igneous rocks are present. A large positive gravity anomaly is also associated with the seamount, indicating an underlying deep-seated intrusion.

The whole structure has been tilted to the SE although when this happened cannot be confirmed.