Department of the Interior, United States Geological Survey, Division uf Geologic Correlation, Washington, D. C, April 1, 1891. ... his knowledge by study of the literature, and by field examination of classic localities, and embody his results in an essay. ... the formations in the various geologic provinces may be classified into three divisions, an upper, a middle, and a lower. ... 13 OUTLINE OF THIS PAPER.
|Title||:||Correlation papers ; Cambrian|
|Author||:||Charles Doolittle Walcott|