These first homes, often called "soddies", were small rooms dug into the side of a low rolling hill. The walls were built up with sod blocks to a height of seven or eight feet. Holes were left for purchased doors and windows hauled from the nearest town or railhead. Cottonwood poles were laid side by side to form a support for a roof made of a thick layer of coarse prairie grass. Over this was carefully fitted a double layer of the sod building blocks. Rain helped the sod to grow and soon the dugout roof was covered with waving grass. Some frontier families found that their cows grazed on their roof, and occasionally had them fall through.