This is Peat which is used in Ireland (and Scotland) as a fuel for fires in homes. It was used extensively in the olden days as it was a cheap fuel. It is cut from trenches (seen in foreground of the right hand picture) in peat bogs using a special long thin spade, and stacked to dry as you see here, then burnt on the fire. Peat bogs are a type of wetland made up largely of dead and decaying vegetation. The ground is spongy and often impassable, making bogs unsuitable for most types of agriculture.
