[7] The Blanco beds were considered to be of lacustrine origin – deposited in a Pleistocene lake basin set upon the Ogallala Formation of middle Pliocene age, which underlies the upper surface sediments of the Llano Estacado.

[8] The local absence of any aquatic/semi-aquatic vertebrates (such as fish, amphibians, microtine rodents, beavers or otters) suggests that the pond was a seasonally drained & shallow basin, like many of the lakes on the High Plains today.

[10] The formation mainly consists of light-gray, fine-grained clay deposits and greenish sand, but indurated sandstone, caliche gravel, freshwater limestone and some conglomerate also are present.

[11] The much more shallow volcanic ash which overlies the Blanco beds matches petrographically to the rhyolite air-fall tephra (Guaje Pumice bed) that underlies ash flows of the Bandelier Tuff in the Jemez Mountains of northern New Mexico, dated to between 1.77 ± 0.44 million and 1.4 ± 0.2 million years.

[9][11][8] The Blanco Beds were once semi-arid grassy plains, with narrow belts of trees fringing watercourses and in the shaded parts of valleys.

[6] Late Blancan faunas are defined primarily on the presence of mammals of the Great American Interchange, and on absolute dates when available.