The Sudbury series is one of the numerous sedimentary deposits found in the pre-Huronian (Archean) division of the pre-Cambrian rocks in the Canadian portion of the Canadian Shield. Other well-known examples are the Doré series, the Couchiching, and the Timiskaming. These ancient sediments furnish evidence upon which geologists hope that some day it will be possible to subdivide the pre-Huronian complex into stratigraphic components, as has been done for the upper, Algonkian, division of the pre-Cambrian. Indeed, some ambitious attempts to do so have already been made, but it will probably be found, as knowledge grows, that these attempts have been premature and erroneous. The stratigraphy and the relation of these Archean sediments to the volcanic rocks above and below needs to be better known before they can be reliably correlated.
Almost every field season since 1925, the writer has had opportunity to study and map the Sudbury series, . . .