212 27/e American Geologist. April, 1895 
At Shreveport it is difKcult to decide wiiether the strata 
exposed should be considered Lignitic or Lower Chuborne, 
although they probably are Lignitic. 
The Mansfield group of Hilgard should in all probability be 
referred to the Lower Claiborne. There is in the Mansfield 
group, so far as we know, a complete absence of animal re- 
mains, the formation being composed of lignitiferous sands 
and claj^s. The characters of the strata, however, are litho- 
logically tiie same as those of the lignitiferous beds that occur 
within the northern part of the Lower Claiborne area between 
the Ouachita and Red rivers. The marine fossils found be- 
tween these two rivers are always both overlaid and underlaid 
by lignitic strata. The Mansfield area lies south, southwest, 
and west of a part of the Lower Claiborne area in which ma- 
rine fossils have been found. Making an approximate deter- 
mination of the strike of the former beds, which is either 
north or northeast, the fossiliferous Lower Claiborne of Bos- 
sier, Webster, Claiborne and Bienville parishes, would be 
along the strike-line of the Mansfield. The inclination of 
these beds is so slight that only by accurate instrumental 
work can their dip and strike be determined with exactness. 
Lower Claiborne fossils have been found in Harrison county, 
Texas,* northwest of the outcrops of the Mansfield; they are 
found north, northeast and eastf of the outcrops of the for- 
mation under discussion in parishes already mentioned, and 
to the south the Mansfield in Natchitoches parish dips under 
the Lower ( "laiborne at Victoria. The opinion has been ex- 
pressed that the beds bearing marine fossils, found in the vi- 
cinity of Victoria, Provencal, Natchitoches, St. Maurice, etc., 
are stratigraphically above the fossiliferous beds found in 
Bossier, Webster, Claiborne and Bienville parishes. 
West of the outcrops of the Mansfield in Texas, + according 
to L. C. Johnson, is Claiborne. As the topography of the 
Mansfield does not represent a basin. ^ such as would suggest 
*Johnsoii. Iron Region of La. and Texas, p. 21, 1888. 
fTlie Tiowcr C'laibornc is cast of llic ISlansficld in N:itchitocii<'s. AViiin 
and Grant i)arishcs. 
J:Iron Regions, La. and Texas; see niai). 
t^ The average altitude along the T. A: P. railw.iy. from Siirex eporl. 
after jiassing out of the rixcr bottom, to Pro\'enc;tl, is'-iSl feet: along the 
v., S. iV V. railroad from Siirevei)ort. after leaving the Ri'd ri\er Ixitlom. 
