San Luis Hills

Each of the separate mountain ranges includes flat-topped mesas and hills, and the ranges trend from the southwest to the northeast. they appear more as hills than mountains, despite rising to eight or nine thousand feet above sea level. The Hills are all within the Sangre de Cristo National Heritage Area. ==Individual ranges==

Fairy Hills The Fairy Hills lie at . They are north of Colorado State Highway 142 and west of the Rio Grande in Conejos County. Brownie Hills The Brownie Hills lie at . They are north of Colorado State Highway 142 and east of the Rio Grande, in Costilla County. Piñon Hills The Piñon Hills lie at . They are south of Colorado State Highway 142 and west of the Rio Grande, in Conejos County. South Piñon Hills The South Piñon Hills lie at . As their name indicates, they are south of the Piñon Hills in Conejos County, and just north of the New Mexico border. ==Geology==

The hills are the exposed parts of an intra-rift horst. They are capped by Miocene basalts of the Hinsdale Formation. The basalt is underlain by Oligocene andesite and dacite volcanic deposits of the lower Conejos Formation. ==Recreation==

The public lands in the San Luis Hills are not developed for recreation. However, some informal hiking trails exist, and mountain climbing and bouldering are possible, especially around the Manassa Dike on south side of Flat Top. ==Protected areas==

The San Luis Hills Wilderness Study Area occupies a tract of land in the Piñon Hills. The wilderness study area was established in 1980 and is owned by the Bureau of Land Management. In 2016, the Western Rivers Conservancy got funding from the Conservation Alliance to purchase a tract in the Brownie Hills on both sides of the Rio Grande, some of it adjacent to or overlapping with the Rio Grande Natural Area. The plan is to transfer the land to Costilla County, which will manage it for wildlife habitat, agriculture, and public open space. ==References==