PEEVIOUS WORK OIST FELOH MOUNTAIN EANGB. ' 379 



In Vol. Ill of the Geology of Wisconsin, published in this year. Brooks, 

 reiterates the views previously published in the Michigan reports. The 

 only new material added is a table (p. 447) giving the estimated minimum 

 thickness for the north belt as 6,200 feet. 



issi. 

 RoMiNGBR, C. Geol. Survey of Michigan, Vol. IV, Part 11, Menominee iron 

 region. New York, 1S81, pp. 155-241. With map. 



This, the first of the reports of the geological survey of Michigan pub- 

 lished while Dr. Rominger was in charge, contains a great number of details 

 concerning explorations in the Felch Mountain range, as it is thus called 

 (p. 194) for the first time in the chapter on the Menominee iron region. 

 The iron-bearing belt along the Menominee River is referred to as the 

 Quinnesee range. 



Rominger criticises Brooks's position with reference to the age of the 

 granite and gneiss along the northern border of the Felch Mountain range 

 as follows: 



Major Brooks declares the granites and the gueisses north of the Felch Moun- 

 tain ore range as youuger than the ore formation, which like them dips northward; 

 but their superposition upon the ore formation is nowhere observable; on the con- 

 trary, the south side of the ore range exhibits in several places the direct superposi- 

 tion of the ore formation on the granite. This fact is known to Major Brooks, but 

 he solves the dilemma by identifying the granites on the south side of the ore forma- 

 tion with the Lauren tian; those on the north side, he claims, represent the youngest 

 Huronian rocks. How he can do so I can not conceive, as the concerned granitic and 

 gneissoid rocks north and south of the ore formation are so absolutely identical that 

 no one who ever sees them can doubt for a moment the quality and age of these rocks. 

 Moreover, this identification of the northern granite with the Upper Huronian, and 

 of the southern with the Laureutian, implies another abnormity; groups of rocks, 

 usually separated from each other by thousands of feet of intervening strata, are in 

 this case thought to be in immediate superposition, which does sometimes occur, but 

 not in coincidence with another improbability like the one stated in this instance 



(p. 207). 



1887. 



Irving, E. D. Is there a Huronian group! Am. Jour. Sci., Vol. XXXIV, 1887, 

 pp. 204r-263, 365-374. Read before the National Academy of Sciences April 22, 1887. 



In discussing this question, Professor Irving takes occasion to refer to 



the structure of the Felch Mountain range: 



In the case of the Felch Mountain belt, which does not exceed a mile in width, 

 all of the strata are described by Dr. Rominger as dipping at a high angle to the 



