Selected stratigraphic sections of Cambrian and Ordovician rocks in Arizona, New Mexico, and western Texas
Information from 68 surface localities that I visited was used in the preparation of a report on the Cambrian and Ordovician rocks of Arizona, New Mexico, and western Texas (Hayes, 1975). Descriptions of the stratigraphic sequence at many of these localities have been published in various reports and a majority of those descriptions are reasonably good if not excellent. The rocks at some other localities are either so poorly exposed or faulted or altered that neither useful nor trustworthy sections are measurable there. Included herein are descriptions of part or all of the Cambrian and Ordovician sequence at three localities where the sections have not been described previously in the literature, at two localities whose excellent sections have previously been presented only in generalized graphic form, and at five localities whose previously published descriptions are at considerable variance with my observations in some way (fig. 1). It is doubtful if interest in any of these sections is sufficiently widespread at this time to justify formal publication of these descriptions but they are presented here for those few persons who may have special interest in them. Enclosed in parentheses following the name of each section is the locality number used in my published report (Hayes, 1975). Color terminology for the rocks are adapted from the Rock Color Chart. Bedding thicknesses, when not given in inches, are approximately as follows: thin-bedded for beds up to 6 inches thick, medium-bedded for beds 6 inches to 2 feet thick, thick-bedded for beds 2-5 feet thick; massive for beds more than 5 feet thick. All the sections in this report were measured with the capable assistance of George C. Cone. Fossil collections referred to in this report are described in Hayes (1975).