EARLIER TERTIARY (EOCENE AND OLIGOCENE). 729 



Catahoula- sandstone. —This formation is thus described by Veatch:'^" 



"Overlying the fossiliferous Vicksburg clays and limestones is a series of sandstones and 

 greenish clays which are generally [very] different, lithologically, from any of the older beds 

 of the Tertiary series in Louisiana and Arkansas. The sandstones which are the characteristic 

 feature of this formation range in thickness from a few inches to 50 or 60 feet, and thicknesses 

 of as much as 140 feet have been reported." These sand beds are often cemented by silica 

 into very hard quartzites, but such occurrences are essentially local, and the quartzitic beds 

 pass laterally in very short distances into soft sandstones or even unconsolidated sands. These 

 sandstones and quartzitic layers have resisted erosion more than the underlying clays and 

 unconsohdated sands of the Eocene and so have formed a line of rocky hihs, the Kisatchie 

 Wold, extending across Louisiana, into Texas on the one hand and into Mississippi on the 

 other. 



"These beds contain no indications of marine life, but land plants are abundant and fresh- 

 water shells have been found in several places. The change from the conditions existing in 

 the Vicksburg is very marked and indicates an elevation during which the region where the 

 oceanic conditions were favorable for the growth of marine life was considerably south of the 

 present outcrop of the formation. 



"These beds were observed at Grand Gulf, on Mississippi River, in Claiborne County, 

 Miss., by WaUes, the first State geologist of Mississippi, who referred to them as the Grand 

 Gulf sandstones.* Later Hilgard" used the name 'Grand Gulf group' to include the beds 

 exposed in southern Mississippi between the Vicksburg and the relatively recent coastal clays 

 (Port Hudson), and the name has been used with varying shades of meaning by diSFerent authors 

 since that time.<* 



"In view of this confusion and in order to furnish a name not likely to be misunderstood, 

 the name Catahoula formation is used in this paper as a synonym for the 'typical Grand Gulf' 

 or the 'Grand Gulf proper.' This new name is from Catahoula Parish, La., which is directly 

 across the Mississippi Valley from Grand Gulf and where there are many outcrops which are 

 lithologically and stratigraphicaUy counterparts of the beds of the old type locality. From 

 this place the beds have been traced eastward through Mississippi into Alabama, where they 

 apparently grade into a series of fossiliferous sands and calcareous clays known as the 'Chatta- 

 hoochee group.' To the west they extend in a very pronounced line across Louisiana into 

 eastern Texas.* The thickness of this formation, as shown by comparative cross sections based 

 on wells at Alexandria and Boyce and on dip observations on Sabine River,-'' is about 1 100 

 feet." 



The Catahoula sandstone in eastern Texas is thus described by Deussen in an impublished 

 manuscript: 



"The Catahoula sandstone lies stratigraphicaUy and conformably above the Jackson 

 formation in eastern Texas and above the Yegua in central and southwestern Texas. It lies 

 stratigraphicaUy and conformably beneath the Fleming clay. It consists of a series of gray 

 and blue sandstones, interbedded with brown, gray, and green clays, gray sands, and a few 

 deposits of lignite. The sandstones in places carry marine fossils; in other places they carry 

 casts of palm leaves, reeds, and great quantities of sihcified and opalized wood. A character- 

 istic feature is the occurrence locally of very hard blue quartzites, which, owing to their superior 

 hardness, resist weathering better than the adjacent materials and appear topographically in 

 the form of hills. These quartzites pass laterally in very short distances into soft sandstones 



and unconsolidated sands. 



\ 



a Kennedy, William, Third Ann. Kept. Geol. Survey Texas, 1892, p. 63. 



b Wailes, B. 0. L., Agriculture and geology of Mississippi, 1857, pp. 216-219. 



cHilgard, E. W., Report on agriculture and geology of Mississippi, 1860, pp. 147-154. 



^ In this connection see the following: Smith, E. A., and Aldrich, T. H., Science, new ser., vol. 15, 1902, pp. 

 835-837; idem, vol. 18, 1903, pp. 20-26. Ball, W. H., idem, vol. 16, 1902, p. 947; idem, vol. 18, 1903, pp. 83-85. 

 Hilgard, E. W., idem, vol. 18, 1903, pp. 180-182. 



« Dumble, E. T., Science, new ser., vol. 16, 1902, pp. 670-671. 



/ Rept. Geol. Survey Louisiana, 1902, pp. 120, 132-135, PI. XXXVII. 



