RECENT EXAMINATIONS 459 



east of the San Antonio Eiver, on j\Iarcelina Creek, some 5 miles north 

 of Palls City, and it marks the extreme eastern limit of this form, so far 

 as now known. The last exposure of clays which we could refer to the 

 Frio was found just east of the San Antonio Eiver, east of which the 

 Oakville overlap concealed it, so far as our sections show. No marine 

 forms were found in it. 



In 1912 and 1913 Balier and Suman spent several months in the Ter- 

 tiary belt between the Brazos and Sabine rivers, the greater part of this 

 investigation being of the post-Yegua deposits, although the beds under- 

 lying the Yegua were given sufficient attention to determine their bound- 

 aries. Large collections of fossils were made, which have not yet had 

 critical study except in special cases. Their reports and notes are very 

 full and satisfactory, but, owing to the heavily timbered character of the 

 country and the scattered exposures, they were unable to fully clear up 

 the situation. The maps prepared by them show their interpretation of 

 the surficial extent of the Marine, Yegua, Jackson, Corrigan, and Fleming 

 from near the Sabine River to the Navasota. They differ somewhat from 

 the published map and report of Deussen, both in their classification of 

 the beds and their boundaries. 



The following descriptions are based principally on a study of their 

 reports, maps, and collections and on personal conferences with them. 

 The work of Kennedy and the writer in the same area has also been used. 



Descriptions of Formations of East Texas 

 lower claiborne 



Yegua. — The lignitic clays and sands of the Yegua are exposed over 

 an extensive area between the Brazos and the Sabine. 



The clays are laminated, thinly stratified, and massive in structure, and 

 chocolate, dark blue, brown, and gray in color. The cone-in-cone struc- 

 ture, noted on Atascosa Creek in the Nueces section, is also found in the 

 basal beds of this area. The sands and sandy clays, which are sometimes 

 micaceous, are brownish drab, buff, and gray. They range from lami- 

 nated to massive and are often cross-bedded. Laminated clays and sandy 

 clays, sometimes leaf-bearing, frequently occur as lenses, pockets, and 

 nodules in the sands, even when the latter are cross-bedded. Similar^, 

 lenses of sand are found in the laminated, jointed clays. 



In the lower portion of the beds the clays seem to predominate. The 

 middle portion seems to carry the most ]i,gnitic matter, and the sands 

 prevail in the upper beds. 



Botli clays and sands weather to light colors, mostly yellow or dirty 



