pense of the Minnesota Iron Company, under the instigation of Mr. George C. Stone. In the report of professor Chester there is evidence that he, in a measure, recognized the differences between the Vermilion and the Mesabi ranges. He compares the Mesabi range with the Penokee-Gogebic range (p. 159) and the Vermilion he compares with the Marquette district (p. 167), yet the influence of the views of professor Irving, whose cooperation and whose notes he acknowledges he received, seems to have caused him to combine them in one sweeping statement that the Vermilion, the Marquette, the Penokee-Gogebic and the Mesabi rocks are all in the same formation, and very similar in lithology and stratigraphic relations. Those differences which he saw he ascribed to the supposed effect of greater folding and metamorphic action. This passage is so strikingly like the statements of professor Irving on this subject that it might have been quoted directly from his notes, viz.:*

"There can be no doubt that the regions described belong to the Huronian. The rocks are many of them typical Huronian rocks, and the whole Mesabi district presents such a strong likeness to the Penokee in all particulars as to make its identity indisputable. That the Vermilion deposits are simply a continuation of the same formation seems also to be a fact. The intricate foldings of the strata account for their vertical position, and the rocks are so nearly like those of Mesabi and bear such similar relations to the Laurentian granites and slates, as to convince one of their identity."

In the same volume (eleventh report) the writer attempted to express in chronological order the formations involved in the northern part of Minnesota (p. 170), based on a concensus of the opinions of other geologists already published. In this. scheme he put all the ores in the Taconic, including those of the Vermilion range, retaining in the "Huronian" only the greenstones and their dependent schists.

The exploration and report of professor Chester, although unfavorable as regards the Mesabi range, resulted in the development of the iron ores of the Vermilion range; and with the commencement of mining began more systematic and more reliable study of the many scientific problems. Hence the work

*Eleventh Report of the Minnesota Survey, 1882 (1884), p. 167.

of professor Chester may always be considered the first step which bore fruit, toward the economic development of the Minnesota ores, if not the first toward the elucidation of their geology. In this statement, however, we should further acknowledge the well-considered prior efforts of Mr. Geo. C. Stone, whose persistent faith in the production of iron ore in Minnesota guided him in the formation of the Minnesota Iron Company, in which was enlisted the money and the good-will of Charlemagne Tower of Pennsylvania. Mr. Stone was sent to the state legislature from Duluth, and was instrumental in securing such favorable legislation as was needed for the organization of capital and the construction of the Duluth & Iron Range railroad.

It was soon after the successful establishment of the Minnesota Iron Company, and the completion of the Duluth & Iron Range railroad, that the writer again visited the mining region. This was mainly in the interest of the commissioners of the New Orleans Cotton Centennial Exposition, but it served also to point to an important generalization respecting the ores of the state. It is published in the thirteenth annual report of the Minnesota Survey, with an ideal illustration showing the geological structure from lake Superior to Vermilion lake (pp. 22, 24), as follows:

"There seem to be three horizons in the strata that, in northeastern Minnesota, have attracted attention for their iron-bearing quality.

"First-The titanic iron of the gabbro belt. This includes the iron ore of the Mayhew location north of Grand Marias, the so-called iron ore of Duluth and Herman and the iron ore that has been reported on Poplar river. This furnishes the iron sand of the Lake Superior beach. This horizon of iron ore seems to have no parallels, so far as reported, in Michigan and Wisconsin.

"Second-The iron ore of the Mesabi range. This is hard hematite and non-titaniferous magnetite. It is that examined in towns 59-14 and 60-14, and is presumably the cause of the iron-ore signs in that tract of country between Okwanim and the Giant's range. It is in the horizon of the Animkie slates equivalents in Michigan.

"Third-The hematite of the Vermilion mines at Vermilion lake. This is on the north side of the granite belt, and in rocks dipping north, the other two horizons being on the south side, and near the bottom of the same, and the probable parallel of the Commonwealth mines in Wisconsin, without any known in rocks dipping south. This iron horizon is lower, in the strata, than either of the others, and seems to be on the hori zon of the Marquette and Menominee iron ores, as is also indicated by the associated quartzites, jaspers and conglomerates."

This separation of the iron ores of the state, and inferentially of the ores of the whole Lake Superior region, into two widely different formations, can be seen to be a very important generalization. Its bearing was not wholly, nor chiefly, scientific. It at once doubled the possible iron output. It pointed to new regions in which to look for iron developments. At the same time, in a geological sense, it was revolutionary-at least it was so considered by the geologists of the south side of the great basin who had settled down upon a convenient theory that the iron-bearing rocks of the Lake Superior region belong entirely to one formation and would be found essentially at the same stratigraphic horizon. The effect of the early hypothesis of the Minnesota Survey, as to the identity of the Vermilion lake ores with those at Gunflint lake was apparently very difficult to eradicate, and for many years it lingered in the literature of the United States Geological Survey. Even yet it appears in the latest expression of that survey on the geology of the iron-bearing rocks, in the form of a bungling hypothesis of a nonconformable junction of two formations at about the horizon of the Vermilion ores, all along that belt of country extending from Vermilion lake northeastward to and beyond Saganaga lake. The opinion had been expressed that the iron-bearing rocks of Minnesota presented the most complex geology of the whole region of lake Superior, and that the simple structural relations could only be seen in Michigan and Wisconsin. It was therefore assumed that the difficulties of the case made it almost impossible to solve the structural problems on the north side of the lake independently, but the solution announced for the geology of the south side must in some way be made to explain the geology of the north side. As a fact, the very reverse is true. The north side is simple

and evident, and the south side, especially in the Marquette region, is complex and difficult. In Minnesota the iron-bearing rocks, in their trend from the northeast, separate from each other so plainly that their distinctness is evident to the most indifferent observer. In Michigan they continue together; they furnish iron ore in valuable amounts at the same points. It is no wonder that they were at first confounded in one formation. The basal conglomerate which is found at the bottom of the upper formation, being itself often a valuable iron ore derived as fragments from the older formation, was put with the ores of the older formation, and its significance as a stratigraphic datum plane was not understood. In Minnesota, where this. basal conglomerate was found, it was but slightly affected by the older iron-bearing rocks, but was seen to vary according to the nature of the underlying rock, being sometimes of granite pebbles or of greenstone or of other schist. This indicated that it had no necessary connection with the older iron-bearing rocks, but transgressed all the older formations indifferently. As this basal conglomerate lay below the upper iron horizon, it required but a moment's reflection to reach the conclusion that the upper horizon must in the same manner transgress all the older formations, and therefore must be a different iron horizon from that underlying the conglomerates.

It would exhaust the patience of this audience, and might not subserve any useful purpose, to enter into the details of this scientific problem, or to relate the curious devices by which some of the geologists who have been engaged on the geology of the rocks on the south side of lake Superior have sought to escape the acceptance of this early differentiation, and, when driven to admit its correctness, have attempted to show that there was really not much difference between the old interpretation and the new, and that the conflicting opinions did not involve anything more than "apparent differences." Suffice it to say, that a party from the Minnesota survey visited the Marquette and the Gogebic iron ranges, and discovered the same differences in stratigraphy as had been announced in Minnesota, and published the fact that certain mines at Marquette were in one formation and certain others in the other, and illustrated this general truth by diagrams, calling atten tion to the consequent agreement with the structure made out

in Minnesota. Since that date the wide extent of the duplicate nature of the iron-bearing rocks of the Lake Superior region. has been unfolded more and more. Most geologists now accept it. The natural result has been, as in most cases when a great truth is admitted in its full scope, that it is carried too far. Numerous other widespread stratigraphic nonconformities have been announced, pertaining to the older rocks, some of which are perhaps well-founded, but others which are probably local and misunderstood because of a misconception of the forces and origin to which the rocks themselves are due.

One of the first fruits of a knowledge of the existence of two iron-bearing series in Minnesota was a systematic effort to develop the iron ores of the Mesabi range at points farther west than the Chester exploration. Mr. John Mallmann, with whom the writer was in correspondence on this subject, conducted the exploration. He was expressly seeking the ores which were presumed to be the northern representative of the Gogebic ores although he was not himself satisfied of their distinctness from the Vermilion ores. This working was done at Mesabi station, on the Duluth & Iron Range railroad. From this point explorations were extended by other parties still farther west, and although there was not good success for a year or two, every test-pit that was sunk to the bedrock confirmed the idea that the Mesabi range rocks were not only iron bearing, but that they were a different set of rocks from those containing the ore at Vermilion lake. In the latter part of 1890 and the first part of 1891 the great discoveries were made which have brought the Mesabi range into the front rank of the iron districts of the world. These discoveries, more than anything else, have emphasized the difference between the ranges, and have called attention to the wide divergence of the interpretation which the Minnesota geologists have put upon the geology of the region from that which had formerly prevailed.

Geological surveys are sometimes accused of not discovering anything. Their function is described to be, to estimate and map out and describe discoveries made by others. They cannot go into the field equipped with the necessary tools for dig ging and blasting. The practical explorer and the actual miner must do that. The explorer is a scout who usually precedes all strictly geological surveying, and the miner is the rank and