Glaciers also deposited numerous granite and limestone erratics on the pavements. The former were carried south across Galway Bay by the second-to-last glaciation. Granite boulders can be found mostly in the north of the Burren. The final ice cover came from the northeast and mostly deposited limestone erratics. On Slieve Elva these are visible today at elevations of up to mabove sea level. The characteristic terracing of the hills occurred when vertical joints weathered and large blocks of limestone fell off and were further eroded away.