Physical Sciences and Mathematics Commons^™

Does The Great Valley Group Contain Jurassic Strata? Reevaluation Of The Age And Early Evolution Of A Classic Forearc Basin, Kathleen D. Surpless, Stephan A. Graham, Jacob A. Covault, Joseph L. Wooden

Kathleen D. Surpless

The presence of Cretaceous detrital zircon in Upper Jurassic strata of the Great Valley Group may require revision of the lower Great Valley Group chronostratigraphy, with significant implications for the Late Jurassic–Cretaceous evolution of the continental margin. Samples (n = 7) collected from 100 km along strike in the purported Tithonian strata of the Great Valley Group contain 20 Cretaceous detrital zircon grains, based on sensitive high-resolution ion microprobe age determinations. These results suggest that Great Valley Group deposition was largely Cretaceous, creating a discrepancy between biostratigraphy based on Buchia zones and chronostratigraphy based on radiometric age dates. These …

Forum On The Flood/Post-Flood Boudary, Marcus R. Ross

Marcus R. Ross

The location of the Flood/post-Flood boundary is an important issue for Flood geology because it is the starting point for a host of research questions. Many papers have been published on this topic, but its placement is still controversial. Three main views are advocated: a low Flood boundary in the Paleozoic or below, a boundary at or near the Cretaceous-Tertiary boundary (now the Cretaceous/Paleogene boundary), and a variable boundary towards the upper Cenozoic but with each geographical area to be evaluated on its merits.

In 2012, Marcus Ross, published a biostratigraphic analysis and argued that a Flood/post-Flood boundary at or …