The Lobato Formation is a sequence of mostly tholeiitic basalt flows that underlies the mesas fringing the northern and northeastern sides of the Jemez Mountains. Major flows include the basalts of Clara Peak, Lobato Mesa, Polvadera Mesa, Escoba Mesa, and Cerro Pedernal. The formation was named for Lobato Mesa (), where the formation is particularly thick and extensive, by H. T. U. Smith in 1938. The formation has a maximum thickness of and is a succession of numerous flows ranging from to in thickness. The flows are mostly olivine-augite basalts, but hypersthene-, pigeonite-, and titaniferous augite-bearing basalts are also found. The formation was erupted between 14 and 7 million years ago, peaking between 10.8 million and 7.8 Mya.