Rock and mineral resources of East Texas

In the past 100 years, more than 100 names have been used to designate parts or all of the outcropping Midway and Wilcox rocks in the Gulf Coastal Plain; less than half of these names are used currently by Coastal Plain geologists, and the validity of some of the remaining named rock units has been questioned in certain recent studies. A compilation of these names shows the development of present-day terminology. Owing to the noncoincidence of certain time-rock and rock units within the Midway-Wilcox section, time, time-rock, and rock terms often have been used indiscriminately, resulting in a terminology that is in part confusing and misleading. Because of the importance and significance of this part of the Gulf Coastal Plain section, a proper definition of time-rock and rock units is desirable; a conceptual distinction of these units is imperative. One logical arrangement is to use the terms Midway and Wilcox strictly as rock terms (group) and to use the terms Paleocene and Eocene as time terms (age). If specific time-rock terms (stage) are needed, such a term as Sabinian is available.