The Cat Hills volcanic field in central New Mexico is a compact cluster of volcanic centers formed during multiple eruptive episodes over millions of years. Its oldest feature, Isleta volcano, formed about 2.78 million years ago as a cone over a maar and is composed of alkali olivine basalt. Los Lunas volcano, an andesite edifice dated to roughly 1.1 to 1.3 million years ago, helps constrain the age of the Ceja surface and Ceja Formation because its lava descended an already formed escarpment. The youngest eruptions, about 0.14 million years ago, produced the 23 cinder cones and broad lava flows of the Cat Hills proper, while nearby Wind Mesa is another related volcanic center.