[1] The Ancha Formation is mostly granitic gravel and sand with some mudstone, derived from the southwestern flank of the Sangre de Cristo Mountains.

Some portions of the formation may have continued accumulating sediments from mountain front canyons east of Santa Fe into the late Pleistocene.

The formation correlates with Pliocene–early Pleistocene aggradation in the Española and Albuquerque Basins, suggesting a regional climate influence on deposition in the uppermost Santa Fe Group.

The good preservation of the Ancha Formation relative to piedmont regions to the south and eroded upland regions to the north suggests that late Pliocene volcanism and tectonism may have provided accommodation space.

[3] The Ancha Formation is a thin (less than 45 m (148 ft) saturated thickness) but locally important aquifer for domestic wells south of Santa Fe.