Seeing stone walls in Ireland’s countryside is as traditional as sipping Guinness in an Irish pub. Most people associate Ireland with being green. It is, thanks to lots of precipitation. For example, Dingle only sees the sun 20% to 40% of the time with an average annual rainfall of 55 inches. Just below the green canopy, however, is a thick layer of blue limestone. For generations, farmers have cleared these rocks from their fields and piled them together to border their property. So why don’t they use mortar? For one, just stacking them is easier. Another reason is livestock learn not to get too close to the walls because they will collapse on their hooves.