\uii- 441 



NOTE i 6. 



Page L09. 



COMPOSITION OF QUARTZ-PORPHYRl OF THE GBEA.1 PALISADES 



Specimen 876, representing the quartz-porphyry of tin- Great Palisades '>t the 



Minnesota coast of Lake Superior contains 71.10 per cent, of silica. 



NOTE 17. 

 Page 110.) 



QUARTZ-PORPHYRY OF BAPTISM RIVER POINT. 

 Specimen 902 has 73.87 per cent, of silica. 



NOTE 18. 



(Page 152.) 



ERUPTIVE MATERIAL IN THE UPPER DIVISION OF THE KEWEENAW SERIES. 



A slight exception to the general absence of eruptive material from theUppei 

 Division of the Keweenaw Series is found in the ohvine-diabase dike described on page 

 2*3 A small exposure of diabase was also noted among the sandstones of the Dpper 

 Division on the Saint Croix River in Sec. 35, T. 44, B. 13 W., Wisconsin, by the late 

 Moses Strong (see Geol. of Wis., p. 424). It is not evident whether this exposure repre- 

 sents a thin intercalated seam or a dike. Both these occurrences are in the lower part 

 of the Upper Division of the Series. 



NOTE 19. 



(Page 224, line 14 from top of page.) 



ERRATUM. 

 T. 40 should read T. 49. 



NOTE 20. 



(Pages 253-258.) 

 THE UNCONFORMABLE CONTACT OF BLACK KIVER, DOUGLAS COUNTY, WISCONSIN. 

 The quotations here given from Mr. Sweeps descriptions *™ «"£££££ 



