A NEW MAP OF PETRIFIED FOREST NATIONAL PARK WITH EMPHASIS ON MEMBERS AND KEY BEDS IN THE TRIASSIC CHINLE FORMATION

Despite many decades of geologic research on the Upper Triassic Chinle Formation within Petrified Forest National Park (PEFO), no published geologic map of the entire park existed until our new map. There are several unpublished maps for specific localities and stratigraphic intervals and a preliminary, unpublished map of the entire Park. The new map presented here was compiled from unpublished and preliminary maps in the PEFO Library and orchestrated into extensive remapping that included several months of field work and color air photo mapping. Data were assembled into ArcGIS and a digital map was prepared. The goals of our project were: 1) to work with PEFO scientific personnel to define a broadly applicable lithostratigraphic model of the Chinle Formation within PEFO; and 2) using this model to field check, update, and refine the existing mapping to NPS Geologic Resource Division standards. The new map makes extensive use of unpublished mapping by George Billingsley (USGS) and Daniel Woody (NAU MS Thesis, 2003) but also incorporates new concepts concerning stratigraphy and paleontology of the Chinle Formation. Past stratigraphic practices typically employed local sections with local names with little regard to correlation of the complex alluvial architecture of the Chinle Formation. This resulted in a plethora of miscorrelated local, informal, terminology. Current work incorporated alluvial architecture and regional correlation of key beds to establish a revised Chinle stratigraphy. The new map reflects this scheme. However, we felt it necessary to tie the new map and stratigraphy into existing nomenclature that has been so critical to the numerous paleontological studies in PEFO over many decades of research. The result is a map that stresses regional stratigraphic correlation, in ascending order Blue Mesa Member, Sonsela Member, and Petrified Forest Member, but relates to long-standing local nomenclature (eg. "Rainbow Forest beds", "Jim Camp Wash beds"). Stratigraphic panels that accompany the map display our proposed correlation of the numerous local names. We hope the new map and panels will encourage future workers to use the new, simplified lithostratigraphic terminology that can then be tied into the long-standing local terms.