A Few Neglected Aspects in Paleontology and Stratigraphy

Abstract

While geology has shown in recent years much progress in various fields, the study in the sedimentary formation seems to have been left behind except for the advancement in the descriptive and systematic petrographic researches of sedimentary rocks., As an important means for the full development of the function of sedimentary rocks as geological and geohistorical records or documents, the observations on the mode and process of sedimentation taking place before our eyes are recommended as important and indispensable., Such observations are to be best carried out at tidal shores, such as that of the North Sea where very interesting and important contributions of R., RICHTER and his colleagues have been done., The tidal zone is the place where variety of sea organisms, especially invertebrates, abounds, and the place where sedimentation takes place; that is, sedimentary rocks with fossil records of life processes are observed, so to say, in the making., That the present is the key to the past is displayed best when the trails, tracks, footprints, burrows, coprolites, etc., left on tidal flats by yarious animals are studies for elucidating and understanding those "surface markings" preserved in rocks of various geological ages., The intimate relations between the sedimentary layers and the inbedded fossils are most accurately understood only when compared with the actual cases observed., On the other hand, those "surface markings", past and present, are indisputably the remains or records of life reflecting their ecological conditions., On the contrary, shell beds, or fossiliferous beds in general, are in many cases, mere heaps of debris of organic origin, as is observed at the present sea shores: sedentary organisms, like reef-building corals, are excepted, of course., The details of the process of sedimentation are the records of the ecological condition of the places of their origin., Such remains as trails, footprints, coprolites, etc., may appear to be, or, perhaps are in many cases, not much worthy as either paleontological or stratigraphical records, because the nature of the organisms that produced them is obscure, on the one hand, and the preservation of such may not be common, on the other., It is very instructive in this respect to think of the case of Tomaculum problematicum, which is ascertained by RITCHER to be a sort of fossilized excrements of a certain animal., Thanks to the efforts of RITCHERS and his colleagues it is now known to be widely distrubuted in the Ordovician formations of Europe and is to be regarded as almost an index fossil., In order that such frail things like the "surface markings" can be preserved fossil, there must be some particular process or processes to be sought., To this problem FREUNDLICH'S Thizotropy may throw some light., The recent tendency of geology toward the high appreciation of the ecological observations as means for the study of stratigraphy and paleontology is embodied in the organization of the "subcommittee on Ecology of Marine Organisms as Related to paleontology" under the Committee of Geology and Geography of the U., S., National Reserch Council., The 10 Reports (1941-1950) contain many important data and suggestions., Finally, the discovery in the succession of the raised coral reef limestone (the so-called Riukiu lilmestone, Pleistocene) of southern Taiwan of a few branchiopod species which had been reported to occur only in northern Japan, warns against the premature conclusion as to the restriction of the distibutional areas of any animals, living or fossil., The occurrence of Eucalathis, a minute brachiopod, in the similar reef limestone of Takao, Taiwan, suggests that the genus can be discovered in the seas lying much toward north from the region from where it has been hither to known. [the rest omitted]