PALEOZOIC TIME — CAMBKIAN. 



465 



UBCOuformability between the Cambrian beds and the Archaean, exempli- 

 fying the fact that the upturned Archsean made the bottom of the Cambrian 

 seas, over which the great sandflats, or other sand depositions, were made. 

 The view also shows that the Cambrian beds had been slightly tilted 

 since their formation. 



505. 



' ^,' I ^ 



tJnconformability at Carp River, Chippewa County, Mich. J. D. Whitney. 



The fossiliferous beds in eastern Newfoundland of the Lower Cambrian 

 consist of shales, sandstones, and conglomerates, of shallow water origin, 

 and are hence evidence that the Cambrian continent stretched eastward as 

 far as the existing continent. It probably had the Pacific for its western 

 border ; for through the investigations, principally of C. D. Walcott, out- 

 crops have been discovered over the Rocky Mountain border to points within 

 500 to 400 miles of the Pacific coast ; and further investigation is likely to 

 carry the discoveries as far west as Archsean ridges exist. 



In the Lower Cambrian region of South Mountain, southeastern Penn- 

 sylvania, west of the Susquehanna and in the adjoining part of Maryland, 

 the Cambrian series overlies unconformably, according to the study of the 

 rocks, and the region, by G. H. Williams and C. D. Walcott, beds and dikes 

 of various igneous rocks, as basalts and rhyolytes, and also tufaceous accu- 

 mulations of the same origin (1S92, 1894). 



The Keweenavj Group, probably Loiver Cambriayi. — No allusion is made 

 above to the Keweenaw group, because it was a local formation. It occupies 

 a belt of country on the south side of Lake Superior, covering Keweenaw 

 Point, where it is best displayed, and extending from thence westward. It 

 is called the copper-bearing sandstone formation from its characteristic 

 rocks and its noted copper mines. But the feature of greatest geological 

 Dana's manual — 30 



