In 1925 the writer attempted to define the limits of the Cretaceous system in Texas and to correlate some of its principal horizons with correspondingly important levels in other parts of the world.1
Conclusions concerning the upper limit were as follows: The Escondido and the upper Navarro were paralleled with the Maestrichtian, and the lower Midway, at least, was assigned to the Danian. In making this correlation it was admitted that the Danian might be Tertiary rather than Cretaceous in age, as so many European geologists had argued. The correlation of the Midway with the Danian was frankly most unorthodox, but reasons advanced supporting it seemed, if not absolutely convincing, at least sufficiently strong to merit serious consideration. In establishing parallelism between the Navarro and the Maestrichtian, and the Midway and the Danian it was, of course, necessary to question the idea of a long-time gap and erosional interval . . .