Jurassic and Cretaceous boundary in the Eastern US and other areas of America: Far from Rhetoric, Closer to Reality

The stratigraphic connection between Early Cretaceous rocks (i.e. Potomac Formation) and the Late Jurassic ones in the Newark Super Group located throughout the Eastern area of the United States has been suggested to be an unconformity by several authors. A 1995 USGS literature review including more than 100 papers, some dated back as far as the 19th Century, reported several problems about Stratigraphic Nomenclature in the US but failed to clarify the issues related to the boundaries between the Jurassic and the Cretaceous. Also, in the 1990´s, a special drill program, the Newark Basin Coring Project cores, was conducted. The project focus was the Triassic-Jurassic, providing abundant information about it but little about the boundary relation between the Triassic-Jurassic (Upper part and the Cretaceous.) The latter is the focus of this paper. This paper is based on the hypothesis that the Triassic-Jurassic Cretaceous-boundary is an unconformity. Based on several field trips to North and Colombia, the hypothesis has grown strongly over the years. The author conducted a literature review about the stratigraphic nomenclature in North America and did several field trips to different regions in Colombia from 2012-2017. The literature review conducted found that the existing descriptions of the relationship between the Newark Supergroup rocks and the Potomac Formation boundary done by different scientists in areas where the Newark Supergroup is covered by Cretaceous rocks, including South Carolina, North Carolina, Maryland, Delaware, Virginia, New Jersey, Connecticut, and New Hampshire suggest an unconformity relationship, however do not provide enough evidence of it. During the field trips to Colombia, the author found vestiges of flat Cretaceous layers over high dipping Jurassic-Triassic in South America, which could confirm the occurrence of a similar phenomenon of unconformity between Jurassic rocks of the La Quinta (North), Girón (Center Andeans) and Saldaña (South Andeans) Formations and Cretaceous continental and marine rocks in Colombia. The existing literature reports there is evidence of similar findings in eastern Canada, Durango-Mexico, Venezuela and Perú. Different scientists have agreed on the hypothesis that there is a Hiatus disturbing a normal geological process of continuous regular sedimentation. However, these authors fell short to explain in detail or provide evidence of all the phenomena occurred. A drill program along Eastern area of the United States the containing stratigraphic contact between rocks of the Newark Supergroup and/or Potomac Group (including Potomac, Raritan, Patapsco, and Patuxent Formations). The author recommends preparing drill program should be rigorous to recover drilling cores for a larger analysis. Similar drilling programs in Canada, Mexico, Belize, Venezuela, Colombia, and Perú, were there are similar conditions, have been reported by other scientists.