Geomorphology of Espanola Basin
— Vincent C. Kelley

The Espanola basin is one link in a chain of six or seven similar basins which comprise the Rio Grande rift or depression and are followed by the Rio Grande from southern Colorado to southern New Mexico. In many respects, it may be considered the type basin owing to the fact that the Neogene Santa Fe Formation or Group has its type sections in the Espanola valley (Baldwin, 1956; Bryan, 1938; Cabot, 1938; Galusha and Blick, 1971; Hayden, 1869; Smith, 1938). Physiographically, the basin is rimmed by alternating ranges and plateaus (fig. 1). The Rio Grande, which is axial to the basin, comes in through a plateau gorge on the north and goes out through a gorge on the south. On the west, the basin boundary is straddled by the great Jemez Mountains volcanic pile. On the northwest, the basin is bounded irregularly by the north- northwest-trending Brazos and Tusas ranges. The northern boundary is the irregularly eroded edge of the Taos Plateau. On the east, the boundary is the Sangre de Cristo Range trend- ing southward from the Picuris Mountains and terminating about 12 mi (19 km) south of Santa Fe. The southern end of the basin is marked irregularly by the cluster of porphyry and volcanic Cerrillos Hills and the northern rim of Galisteo River valley, an eastern tributary of the Rio Grande (fig. 2). The southwestern margin is taken at the La Bajada fault escarpment and the Cerros del Rio volcanic hills. Both the valley and the basin are centered about the confluence of the Rio Grande and its principal tributary, Rio Chama, which drains into the basin from sources along northeastern areas of the Colorado Plateau. These rims are fed in the basin area by numerous tributaries from the surrounding mountains. Notable among these are: El Rito and Ojo Caliente on the northwest; Embudo, Truchas, Santa Cruz, Pojoaque-Tesuque and Santa Fe on the east; and Santa Clara and Frijoles on the west. Altitudes along the Rio Grande through the basin are 6,050 ft (1,845 m) on the north down to 5,300 ft (1,616 m) on the south. Altitudes in the surrounding mountains range up to 13,101 ft (3,994 m) in the Sangre de Cristo Range; 11,551 ft (3,522 m) in the Jemez Mountains; and 8,602 ft (2,623 m) in the Brazos and Tusas mountains.