Facilities for milling lumber were almost non-existent: workers used stone axes and crude saws to shape the wood, and often used logs which only had their bark stripped from them. These methods gave mission structures their distinctive appearance. Timber was used to reinforce walls, as "vigas" (beams) to support roofs, and as forms for door and window openings and arches. Since most of the settlements were located in valleys or coastal plains almost totally devoid of suitably large trees, the padres were in most cases limited to pine, alder, poplar, cypress and juniper trees for use in their construction efforts. Indians used wooden "carrettas", drawn by oxen, to haul timber from as much as forty miles away (as was the case at Mission San Miguel Arcángel). At Mission San Luis Rey, however, the ingenious Father Lasuén instructed his neophyte workers to float logs downriver from Palomar Mountain to the mission site. The lack of good-sized timber forced the men to design mission buildings that were long and narrow. For example, the widest inside dimensions of any of the mission buildings (at San Carlos, Santa Clara, and Santa Cruz) is : the narrowest, at Mission Soledad, spans . The longest structure, at Mission Santa Barbara, stretches . Stone ("piedra") was used as a construction material whenever possible. In the absence of skilled stonemasons, the inexperienced builders resorted to the use of sandstone; though easier to cut, it was not as weather-resistant as that which would have been used by skilled artisans. To bind the stones together, the priests and Indians followed the (Mexican) Pre-Columbian technique of using mud mortar, since mortar made from lime was unavailable to them. Colored stones and pebbles were added to the mud mixture, giving it ""a beautiful and interesting texture"."