While in its broader features the Cretaceous of western Texas and of the northern portion of the Mexican state of Coahuila corresponds closely with that of the Colorado River section east of it, there are, nevertheless, many important differences in the stratigraphy and faunal relations well worth more detailed study than they have yet received. A few of these differences, which have come under my personal observation during trips made through various parts of the region, are presented as indicating the general character of the formation.
Only a few remnants of areas are found north of the Texas and Pacific railroad, and that line may well be taken as marking the northern boundary of the Cretaceous deposits of western Texas, since, as a body, they pass north of it only (if at all) under that portion of the road which . . .