Rockall Helen's Reef (the latter was named in 1830). Notes Bibliography Rockall Rockall () is a British uninhabited granite islet located within the exclusive economic zone (EEZ) of the United Kingdom, situated in the North Atlantic Ocean. Its approximate distances from the closest large islands are: west of Scotland; northwest of Ireland; and 700 km (440 miles) south of Iceland. The nearest permanently inhabited place is North Uist, an island in the Outer Hebrides of Scotland, 370 km (230 miles) to the east. The United Kingdom claimed Rockall in 1955 and incorporated it as a part of Scotland in 1972. Ireland
Benue Trough under oxygen-deficient bottom conditions. In the Upper Cretaceous, the Benue Trough probably formed the main link between the Gulf of Guinea and the Tethys Ocean (predecessor of the Mediterranean Sea) via the Chad and Iullemmeden Basins. Towards the end of this period the basin rose above sea level, and extensive coal forming swamps developed, particularly in the Anambra Basin. The trough is estimated to contain 5,000 m of Cretaceous sediments and volcanic rocks. A common explanation of the trough's formation is that it is an aulacogen, an abandoned arm of a three-armed radial rift system. The other two arms continued