AMERICAN GEOLOGY DEOADK OF 1860-1869. 



537 



This view, so modestly put, contains in it, however, the germ of 

 the conclusions arrived at. by Van Hise some twenty-five years later." 



He noted the monoclinal character of the deposit at the Washington 

 mine property in the Marquette region, and described the ore of the 

 Lake Superior specular and hematite workings and the Barnum mine 

 as occupying the position of "the frustum of a hollow cone lying 

 with its axis horizontal and its small end toward the east, 1 ' which had 

 been cut in two by a horizontal plane representing the surface of the 

 ground. 



Other points, which it is well to note, since Rominger in his later 

 report had occasion to disagree with him, are his regarding the ores 

 of the Cascade Range as the equivalent of the Michigan and magnetic 

 ores of the Mishigaini district and as older than any of the iron beds 

 in the Republic Mountain series; and, sec- 

 ond, the Felch Mountain ore deposit as lie- 

 longing to the lower quartzite, the ore itself 

 resting immediately upon and being bounded 

 on the south by hornblendic, micaceous, and 

 gneissic rocks which are undoubtedly Lau- 

 rentian. Subsequent studies by Wadsworth, 

 Van Hise, and others have shown him to be 

 substantially correct in both of these con- 

 clusions. 



Ill health prevented Brooks from carry- 

 ing out his work in as thorough a manner 

 as he wished, and his letter of transmittal 

 was written from London, he having gone 

 abroad to recuperate. 



Brooks, as may readily be inferred, was an eminently practical man. 

 Indeed, his entire training was of a practical nature, consisting of two 

 years at the School of Engineering of Union College and a single 

 course of lectures on geology under Lesley at the Uni- 

 sketch of Brooks. versity of Pennsylvania. His early work was in con- 

 nection with land surveys, but after his retirement 

 from the Army in the fall of 1864 he served a year on the geological 

 survey of New Jersey under Cook, and then in 1865 became vice- 

 president and general manager of the Iron Cliff mine, near Negaunee, 

 in the Marquette district of Michigan. Here he began that geological 

 work upon which is mainly based his reputation. The difficulties 

 which he encountered were such as can be scarcely comprehended by 

 those who have not visited the region. The country was, much of it, 

 heavily forested and swampy as well. Outcrops were few and perhaps 

 wholly obscured by the drift or by undergrowth. There were no maps. 



Fig. 80.— Thomas Benton Brooks. 



"Monograph No. XXVIII, U. S. Geological Survey, 1897. 



