186 MICHIGAN ACADEMY OF SCIENCE. 



sandstone growing coarser and coarser and culminating in red beds 

 and conglomerates, and emergence of the laud and a cessation of de- 

 posits. This series is known as the I'ortage-Chemung-Catskill, and all 

 these rocks are supposed to belong to the Devonian, representing plainly 

 part of one physiographic cycle. Now when we come to Michigan we 

 find a similar lithological and physiographic succession. Beginning with 

 the black shales, which Winchell called Huron, and we now call Antrim, 

 we have a similar succession passing through blue shale, blue and green 

 sandy shales and sandstone to heavy sandstone. It was natural for 

 the New York Geologists to correlate them with their own series, but 

 Winchell found that the uppermost beds of this series, which he called 

 the Marshall Group, were fossilferous, especially in the lower part, 

 the upper part being a heavy sandstone in which fossils are rare. These 

 fossils he maintained were distinctly Carboniferous in character and 

 though the controversy lasted some time there is no doubt that he was 

 right, so that at least the upper part of this series must be put into the 

 Carboniferous, just how much it is often hard to tell. We have here 

 a case in which the progress of geographic evolution and that of organic 

 evolution did not keep pace. The continent emerged earlier in New 

 York than in Michigan and the fauna did not migrate paripassu. 



We have now the geology of the State mapped out in broad and gen- 

 eral outlines, except that very little was yet known regarding the de- 

 tailed superficial geology, except that the lakes had once been higher 

 and retired and that the ice had once played a much greater role in dis- 

 tributing erratics. Mr. Leverett takes up this matter so that for me 

 there remains only to describe the work of correction and filling in, and 

 yet this is of no mean importance, either theoretically or practically. 

 The next geological survey was started in ISGl). It is worthy of remark 

 that just as Michigan has very strong State Institutions, while the pri- 

 vate colleges are comparatively weak, so most of what has been done 

 geologically-, has been done ofliciall}', and we have not had that wealth 

 of information which in other States has come from private initiative. 

 One exception to this is in the work of the Kent Scientific Institute about 

 at this time, — another is of the Lake Superior Mining Institute at pres- 

 ent. Of course much of the scientific information has been gathered by 

 State Officers from developments made for private ends, with their test- 

 ings, drillings, etc. In 1861) the Survey as re-organized'" had Alexander 

 >Vinchell at its head, but the laboring oars were taken by Brooks on the 

 iron bearing rocks, I*umpelly on the copper bearing rocks, and Rom- 

 inger on the sedimentaries. Mr. Brooks' work introduced to the field a 

 number of names prominent here and elsewhere, such as H. Credner, 

 A. A. Julien, Chas. A. Wright, Regent C. D. Lawton, Jacob Houghton 

 and others. It contains a valuable treatise on the tracing out of the 

 stratigraphy of the very complicated iron regions b}- means of belts of 

 magnetic attraction. It contains also a lot of microscopic descriptions 

 which should mostly be replaced by later and more accurate work of the 

 r. S. Geological Survey. In the field the distinction between the horn- 

 blende and augite was not satisfactorily made and the geological rela- 

 tionships of the rocks called diprites, which are largely altered augitic 

 rocks was not understood. Nevertheless, in the matter of detailed stratig- 

 raphy of the iron bearing rocks, very great progress was made and a 



