There are two groups of Moine rocks of low to mid-amphibolite facies in Shetland that may have been separated by a distance of 200km before they were brought to their present relative positions by movements along the Walls Boundary Fault (WBF). Those west of this fault are possibly of shallow water origin and have been tentatively correlated with the Morar Division of the Scottish Moine. The Moine sequence to the east of the fault, The Yell Sound Division, is about 10km thick and is made up of psammites that have been gneissified to various degrees. These psammites lack any relic shallow water structures so may be of deeper water origin. Unlike those west of the WBF, these rocks contain garnet-studded hornblende schists and have been correlated with the Glenfinnan and Loch Eil groups of the Scottish Moine.