Diastems in the Pecan Gap chalk of Travis County, Texas

The importance of the recognition of diastems, in attempts at detailed microfaunal zonation of marine strata, is discussed. Three diastems are described, occurring in an exposure of Pecan Gap chalk (Upper Cretaceous, Taylor group) near Austin, Texas. The presence of encrusting foraminifera on casts of mollusks is indicated as evidence for the existence of a diastem.