Btw. pgs. 67 and 111. Zia marls. Bluish-yellow Eocene marls, 0 to 40 feet thick, forming cap rock on one side of Rio Grande. Called Pleistocene by Herrick. Rest on soft red and gray Eocene sandstones, and unconformably underlie Pliocene calcareous sandstones and conglomerates of white to deep-green color. Present in north-central New Mexico (Sandoval County). Age is Eocene(?).
[Probably named from village of Zia, near Jemez, Sandoval Co., central northern NM.]

Source: US geologic names lexicon (USGS Bull. 896, p. 2394).

Zia Marl and Jemez Marl are here abandoned. Both were named by Reagan (1903). Zia was listed by Wilmarth (1938) and Keroher and others (1966) as questionably Eocene. Wilmarth further noted that Herrick (1898) called Zia Pleistocene. "It is clear that the term Zia Marl should be abandoned, for it is preoccupied by Albuquerque Marl and, furthermore, is not an Eocene formation. It should be noted that the term Albuquerque Marl was applied to deposits occurring on several erosion surfaces besides that of the Llano de Albuquerque. Bryan and McCann (1938) named two such later surfaces. Reagan (1903) did not recognize that his Zia Marl was the same as Herrick's Albuquerque Marl, but used the term Albuquerque Marl as follows: 'The Pliocene rocks in the Rio Grande embayment which are identical with the Jemez marls, just described, will be here called the Albuquerque marls. These marls are a continuation of the Santa Fe marls of Cope, a part of which was identified by him when at Algodones in the seventies.' In the interest of stability of stratigraphic nomenclature, we believe that the terms Jemez Marl and Zia Marl should be abandoned. Neither of these has been published since originally proposed (Reagan, 1903), and in each case the names were applied to beds with prior names. Moreover, the ages allocated by the original authors give an erroneous stratigraphic position to the formations, which probably accounts for the disuse of the terms."

Source: GNU records (USGS DDS-6; Denver GNULEX).