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University of California . 



[Vol. 3. 



much more profound than the breaks which exist between the 

 Paleozoic and the Mesozoic, or between the Mesozoic and the 

 Tertiary. The formations on the proximate side of that Interval 

 are very much more closely connected with those of the Paleo- 

 zoic, both in their physical characters and in their time of 

 accumulation, than they are with anything' on the far side of it. 

 The mere failure to find fossils in the strata is but a poor reason 

 for grouping them with the metamorphosed elastics beneath the 

 great gap. Any pre- Paleozoic subdivision of the time scale 

 co-ordinate in value with the Paleozoic naturally has the 

 Eparchsean Interval for its upper limit, and the Algonkian, being 

 upon the proximate side of that break, should be regarded, as 

 above suggested, as a subdivision of the Paleozoic co-ordinate 

 with Cambrian . 



The preconceived theory involved in the original impossible 

 definition of the term Algonkian, that the Archaean is composed 

 of non-clastic rocks, the fascination that seems to have attended 

 the erection of the new division of the geological scale, and the 

 natural desire to magnify its import, seem to have obscured the 

 great significance of the Eparchsean Interval and the remarkable 

 irruptive relationships which exist between the Archaean plutonic 

 rocks and so much of the sedimentaries with which they are 

 associated. In this obscuration of the Eparchsean Interval and 

 in the slurring over of the irruptive relations of granite gneisses 

 to the metamorphic elastics and volcanies of Dana's Archaean, 

 we have serious objections to any term used in the sense which 

 it has been sought to give Algonkian. It is extremely doubtful, 

 moreover, whether we know at the present time any "Ancient 

 Crystallines," such as are reserved for the Archaean in the pro- 

 posed new sense, which antedate the oldest elastics. Certainly 

 the more these rocks are studied the more generally do they 

 appear to be intrusive in the oldest elastics. We cannot, there- 

 fore, refer these "Ancient Crystallines," so far as we know them 

 at present, to anything but the Algonkian, if that term is to 

 include the pre-Cambrian elastics. This conclusion of course 

 throws Archaean not only out of stratigraphy, but also out of 

 geology. The term Algonkian is thus not merely in direct 

 conflict with Archa?an in the established use of that term, but it 



