Recent marked tendency shown in Europe especially to give taxonomic rank comparable to geological period, Carbonic, Cretacic, and the like, to rocks older than those of Cambric age, and to designate the rock column represented Precambian appears to be, in this country at least, a notably retrogressive movement. It parallels the situation a century ago when Wernerians were possessed with jumbling together all rocks beneath those of Cretacic age, as we know them today, under the title of the Transition Class. Out of the latter speedily take on form six great systems. Thus, late delimitations of Precambrian imply its recognition as having Systemic or Periodic rank, a rank much too low.
Proceedings of the Iowa Academy of Science
©1929 Iowa Academy of Science, Inc.
"What Shall We Do with Precambrian?,"
Proceedings of the Iowa Academy of Science, 36(1), 277-278.
Available at: https://scholarworks.uni.edu/pias/vol36/iss1/67