Palaeoenvironmental and palaeoecological analyses of late Frasnian (early Late Devonian) strata and fauna in New York and the central Appalachians of the United States reveal strikingly similar patterns of basin filling and evolution. Marine environments of both the upper West Falls Group in New York and the lower Foreknobs Formation in the central Appalachians were characterized by rapid delta progradation and steep offshore submarine gradients. Following a brief marine transgression, basin conditions of the overlying Java Group in New York and the upper Foreknobs Formation in the central Appalachians were quite different. Sedimentation decreased in intensity and the basin was much shallower, with a broad sublittoral shelf and gentle offshore gradients. The gentler environmental gradients of Java-late Foreknobs time yield a three-fold pattern of community development along an onshore-offshore transect in contrast to a two-fold pattern in the earlier late West Falls-early Foreknobs environments. Communities characteristic of deep water environments earlier in late West Falls-early Foreknobs time are displaced farther offshore in Java-late Foreknobs time, and outer platform and prodelta regions develop diverse species assemblages not present previously.
All Science Journal Classification (ASJC) codes
- Ecology, Evolution, Behavior and Systematics