Page:The Journal of geology (IA journalofgeology21894univers).pdf/72
ascertained, is permanent. The rocks in question well illustrate the confusing synonomy which arises from the employment of time names. They have been called at various times and by various writers: Silurian, Old Red, Carboniferous, Lower Carboniferous, Permian, Upper Permian, Mesozoic, Older Mesozoic, Secondary, Middle Secondary, New Red, Trias, Jura-Trias (and synonyms), Keuper, Upper Trias, Rhætic, Lias, Inferior Oolite, and Oolite.
When the chronological relations of a stratigraphic unit have been established, it becomes proper to apply to it the title of any time division including its period of formation; but the need for a local stratigraphic name, or, in other words, an individual name, does not cease. The place of the Hamilton group in the time scale is so well known that it is properly called Devonian and Paleozoic, but the local name Hamilton is still useful.
In the conceivable case of a formation or group representing the whole of a division of the time scale and more more, there might be a question of the need of a local name. But the existence of such a case has not been demonstrated, and it must be admitted that in the great majority of instances the local stratigraphic units are incommensurate with the standard time units. The body of rocks under consideration is imperfectly supplied with fossils, and little is known of the relations of its fossiliferous horizons to one another and to the upper and lower limits of the series. No one asserts that its period of formation was coëxtensive with any of the time divisions whose names have been provisionally applied to it. Opinions as to the interpretation to be given to its fossils are still divergent, and the only name which can be conveniently used by all is one which avoids the question of correlation. A local geographic name meets this requirement.
There are valid objections to a paleontologic or a purely petrographic name, but as such have not been proposed the objections need not be stated.
3. The proper geographic term is Newark.—Prominent among the qualifications of a geographic term for employment in strati-