190 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 75 



names for newly defined units and groupings of units. This will mean 

 the dropping of old names, the meaning of which has been the subject 

 of controversy, and those whose authors have included under one term, 

 through lack of information or because of preconceived ideas, units 

 that may belong to one or more systems. Without doubt we should 

 endeavor to preserve names given by pioneer workers, but not at the 

 sacrifice of clarity or the advancement of knowledge. The long and 

 bitter controversy of Murchison and Sedgwick over the terms Silurian 

 and Cambrian was largely the result of the lack of information and 

 was injurious to the progress of geological science. 



The rules for geological nomenclature formulated and promulgated 

 by the International Geological Congress are most helpful and if 

 followed by geologists will be of great assistance not only to the 

 professional geologist but to all instructors, students, engineers, and 

 laymen who have occasion to refer to geological literature. 



SAWBACK FORMATION 



The name " Sawback " formation was proposed by Dr. John A. 

 Allan in 191 3 for the formations lying beneath the known Devonian 

 of the Sawback Range.' Not finding any fossils, he. tentatively re- 

 ferred the entire series of limestones and shales, estimated to have a 

 thickness of 3.700 feet (1,127.8 m.), to the Devonian. This was 

 repeated without reservations in 1915/ but in 1916 Allan reported* 

 that in oolitic beds west from Mount Edith numerous fragments of 

 Cambrian trilobites occur ; that the beds containing them may be 

 correlated with the Paget formation, and the shales beneath with the 

 Boswortji formation ; and that the gray arenaceous limestones at the 

 base of the section correspond to the Middle Cambrian Eldon forma- 

 tion. He mentions having found salt crystals in a shale series beneath 

 the oolitic limestones and that this indicates a continental origin for 

 the shales. These shales are now referred to the basal Upper Cam- 

 brian Arctomys formation. Allan thus includes in his Sawback forma- 

 tion, as we now know it, one Ozarkian, three Upper Cambrian, and 

 one Middle Cambrian formation. 



L. D. Burling states in his report of field-work for 1915* that 

 Dr. E. M. Kindle had found in 191 5 Cambrian fossils in the upper 

 part of the Sawback formation, and that he (Burling) had collected 



'Summary Rep. Geol. Surv. Canada for 1912 (1914), p. 172. Twelfth Int. 

 Geol. Cong. Guide Book, No. 8, pt. 2, p. 182. 

 'Summary Rep. Geol. Surv. Canada for 1914 (iQiS), p. 43. 

 'Summary Rep. Geol. Surv. Canada for 1915 (1916), p. 102. 

 * Idem, p. 99. 



