At the base of a bed of flysch sandstone of Eocene age in the Jaca area of the Aragon river valley (Spain), occur rosette type markings about fifty centimeters in diameter consisting of shallow grooves radiating from a central cone-shaped impression. They are believed to be marks left by large pelecypods.
Analysis of the Niesen flysch between Le Sepey and Mosses lake does not confirm the deep-water bathymetry commonly attributed to flysch deposits. The juxtaposition of organic material over continental alluvium--a typical flysch characteristic--was observed only at shallow depths. The muddy sands, source of the flysch deposits, are actually formed at shallow depths. Bird tracks reported from certain flysch beds also suggest shallow-water origin for the deposits. Cross currents produced after periodic disruption of tectonic and climatic equilibria in parts of a marine basin corresponding to the continental platforms explain the mechanical sorting of the organisms and detrital material as well as the granoclastic structure of the flysch. After deposition of the flysch and before its compaction orogenic mobility at the bottom of the basin affected the petrography of the flysch causing corrosion of the quartz and feldspars at the moment of consolidation. Evidence presented by proponents of a deep-water origin for the flysch deposits--based on foraminifera and the petrographic and paleo-oceanographic characters of the deep-water sands--is reviewed.
Nodules in Toarcian (Jurassic) limestones at Saint-Antonin in the valley of the Aveyron, southwestern Quercy, France, which resemble oolites but lack the concentric structure, are described and attributed to deposition of calcite around a nucleus in one single stage. Petrographic study of the limestones also reveals that dolomitization, phosphatization, and silicification have taken place simultaneously, probably as a result of biochemical processes.
Petrographic and geologic observations on the Flysch deposits of the French and Swiss Alps, the Romanian Carpathians, the northern Apennines (Italy), and the French and Spanish Pyrenees show that there are two distinct groups of formations. The first group consists of true Flysch deposits, but deposits of the second group are comparable to marine molasse beds. The petrographic and geologic characteristics of the two types are compared in a table, and examples of each are given.
Study of the lithologic and faunal composition of Danian limestones of the eastern part of the Cretaceous trough at the foot of the north slope of the French Pyrenees leads to the conclusion that a variety of petrographic types is present and that the so-called lacustrine limestones were formed in a marine basin in which lacustrine conditions were produced at times by the introduction of fresh waters from rivers flowing down ranges bordering both sides of the trough.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.