THE LOWER PALAEOZOIC ROCKS OF SOUTH-WEST MURRISK, IRELAND

Abstract

The general geology of an area of Ordovician and Silurian rocks in North Connemara is described. The oldest strata are the Arenigian Sheefry Grits, a thick marine series of slates and greywackes derived from the south. Many of the beds exhibit perfect grading; they are thought to be the deposits of turbidity currents. The Glenummera Slates follow conformably, and are succeeded by the deltaic Mweelrea Grit series, of Middle Ordovician age. Marked facies changes show that the source of sediment lay to the south, and many of the conglomerate pebbles can be referred to the Connemara Schists.