60 GEOLOGICAL SURVEY OF WISCONSIN. 



The ancient artificial mounds, especially those of imitative forms, 

 found within the district surveyed by Mr. Strong, have received a 

 share of his attention. They were built in prehistoric times, by an 

 extinct race of people, whose existence here is believed to have been 

 with that of the Mastodon. They thus form the connecting coeval 

 link between the geologist and antiquary; the duties of the one cease, 

 while those of the other commence with the epoch of the mound 

 builders. 



SURVEYS IN OCONTO COUNTY, BY MAJOR T. B. BROOKS. Maj. 

 Brooks, late of the geological survey of the state of Michigan, under- 

 took to trace the Iron-bearing, and other rocks found on the east side 

 of the Menomonee river of Green Bay, above Sturgeon Falls, across 

 that river into Wisconsin, and to ascertain as far as was practicable 

 their southern and western boundaries, where they are succeeded by 

 granitic rocks. Special search was to be made with the aid of the 

 " mining compass " and otherwise, for iron ores, but the money ap- 

 plicable to this survey not being adequate to the sinking of exper- 

 imental pits, shafts, or drifts, such work was necessarily left to private 

 enterprise, guided by the results of such survey as he should be able 

 to make. A suit of specimens was to be collected and forwarded to 

 the chief geologist, with a full report in detail, illustrated by the ne- 

 cessary maps, sections and diagrams. All chemical analyses were to 

 be made by Prof. Daniells, of Madison. 



Maj. Brooks commenced active operations in the woods witli 

 ample assistance and supplies, on the 10th of August, and the work 

 was continued fifty-six days. The weather, with slight exceptions, 

 proved favorable; and the report of results will show that each per- 

 son engaged must have done his whole duty. His camps were moved 

 along the course of the river, from which he extended his observa- 

 tions south to the outcrops of the granite, and west, as far as the 

 " Great Swamp," in range 17 E., town 40 1ST. He was thus able, 

 though not without much exposure and difficulty, to accomplish all 

 the objects proposed, and in a satisfactory manner. 



It is gratifying to know that his report, now being prepared, will 

 show that the Iron range extends across the Menomonee into Wis- 

 consin, and that there is a strong probability that it will hereafter be 

 found to contain, within this state, workable beds of ore. 



The rocks examined, as in other portions of the Archaean regions, 

 were found to be quite local in extent, and often gradually passing, 

 by insensible degrees, from one to another, rendering it very difficult, 

 if not impossible, to distinguish the different kinds, and to classify 



