The Otero Formation, Pleistocene lacustrine strata in the Tularosa Basin, southern New Mexico
— Spencer G. Lucas and John W. Hawley

The Otero Formation is gypsiferous clay and sand, gypsite, and associated fluvial-deltaic facies deposited in and adjacent to Pleistocene Lake Otero in the Tularosa Basin of south-central New Mexico. This lithostratigraphic unit, which excludes Holocene eolian and playa sediments of the White Sands-Lake Lucero-Alkali Flat area, forms much of the surficial basin fill at elevations below 1220 m. The formation's areal extent is a least 2100 km²; and, it is widely exposed in parts of Doha Ana, Otero and sierra Counties. Originally named by C. L. Herrick in 1904, the term Otero Formation has never been used by subsequent workers. The Tularosa Formation, also named by Herrick, comprises strata that we include in the upper part of the Otero sequence. We define a lectostratotype section for the Otero Formation and review its lithotypes, distribution, thickness and age. Further study is needed to (1) decipher climatic and geomorphic history recorded by these lacustrine and fluvialdeltaic sediments, and (2) better define the formation's lateral and basal (subsurface) boundaries.