June 11, 1915] 



SCIENCE 



863 



Professor Gilbert Gusler, of tlie Ohio 

 State University, has been appointed to a 

 position as associate in the department of 

 animal husbandry of the University of Illi- 



DISCVSSION AND COBBESPONDENCE 



COMPLEXITY OP THE ALEXANDRIAN SERIES 



Under the tacit encouragement of our federal 

 and state geological bureaus the unfortunate 

 practise of continually displacing already well- 

 defined and useful terranal titles by new ones, 

 often of very doubtful utility, with the idea 

 in mind that such continual change in nomen- 

 clature is the only essential element in the 

 advancement of knowledge, seems to be nota- 

 bly increasing rather than showing any appre- 

 ciable signs of wane. Lest the shadow perma- 

 nently be mistaken for the substance every 

 contemplated case of renaming demands be- 

 forehand the closest scrutiny. 



It was a similar tendency, a generation ago, 

 that led the various geological surveys to dis- 

 pense with the services of the paleontologist 

 and to adopt the lithologic unit in stratigraphic 

 classification and in cartographic representa- 

 tion. In new form the remaining mania still 

 refuses to be downed. 



A recent concrete case is the proposal of the 

 name Alexandrian for an Early Siluric series 

 in the Mississippi Valley. This instance is 

 no worse than a multitude of others. It is 

 selected at random, chiefly because it illus- 

 trates in small compass more points than any 

 other that comes to mind. Moreover, it em- 

 phasizes three facts of universal application. 



There is first the doubtful expedient of 

 erecting groups so large as that of series by 

 merely throwing together all strata lying be- 

 tween two well-known horizons. Second, there 

 is the pernicious habit of making inconse- 

 quential additions to or subtractions from al- 

 ready defined formations and proposing there- 

 for entirely new names, when the old terms 

 easily answer without violation of a single 

 canon of nomenclature. In the third place 

 there is little or no consideration of paleo- 

 geographieal conditions. Until the last-named 

 factor is recognized in something of its true 

 perspective there can be little real progress in 



the solution of the broader problems of local 

 statigraphy. 



Now the Siluric section of northeastern Mis- 

 souri is quite remarkable because of the fact 

 that it is so meagerly represented, because it 

 is divided medially by a marked plane of un- 

 conformity, and because there is an overlapping 

 of a southern earlier Siluric deposition by a 

 northern later one. 



In the proposal of the term Edgewood forma- 

 tion to include the Bowling Green limestone, 

 the Noix oolite, a local phase of what was later 

 called the normal Noix limestone as noted by 

 Ulrich, and the lower normal limestone to 

 which recently the name Gyrene limestone 

 was given, the significance of the notable plane 

 of unconformity at the base of the Bowling 

 Green member was completely overlooked. It 

 now transpires that the stratigraphic aflinities 

 of this formation are with the northern, or 

 Iowa, section instead of with the southern or 

 southern Missouri sequence; that its time rela- 

 tions are with the Mid Siluric rather than with 

 the Early Siluric sub-period. In consequence 

 of these facts Edgemont as a terranal designa- 

 tion becomes at once invalidated. 



By slight change in the original significa- 

 tion of the term ISToix, as applied to a limestone 

 member, this name assumes a useful and valid 

 role. The appellation Gyrene for a limestone 

 becomes wholly unnecessary. If in the north 

 Missouri region the term Alexandrian series 

 is to be retained as a permanent stratigraphic 

 title with a taxonomic rank of series it wiU 

 have to be restricted in its application to the 

 Siluric strata below the plane of unconformity 

 marking the base of the Bowling Green lime- 

 stone. 



According to the rule of nomenclature laid 

 down by its author the term Alexandrian would 

 have to be abandoned and a new title proposed. 

 There is urgent need of a serial term for 

 the Early Siluric section of the Ozark 

 region. It appears a happier treatment of 

 the problem to retain a name already in use, 

 modifying its delimiting application slightly 

 to meet the exigencies of newly discovered rela- 

 tionships. Only in this way can the interests 

 of stable geologic nomenclature be best sub- 



