132 NINTH REPORT. 



SOME INTERESTING GLACIAL PHENOMENA IN THE MARQUETTE 



REGION. 



Charles A. Davis. 



(By permission of Alfred C. Lane, State Geologist.) 



ABSTRACT. 



(A full account will l^e i:)ublished in a forthcoming report of the Michigan 

 Geol. Survey.) 



During the field season of 1906 the writer was assigned by the State Geol- 

 ogist, Dr. A. C. Lane, the work of completing the soil survey of the North- 

 ern Peninsula of Michigan, begun two years before by Professor I. C. Russell, 

 and continued by him and Mr. Frank Leverett of the U. S. G. S. during 1905. 

 In addition to the soil survey, attention was given to mapping the glacial 

 features and to other surface phenomena, and it is to some of the glacial 

 records and their interpretation that attention is called by this paper. 

 ' The region unmapped lay to the west of a line south from Marquette 

 and north of the south line of Tp. 43 N., and amounted to more than 200 

 townships, or, in round numbers, 7500 square miles, much of it in nearly 

 primitive condition without roads or settlements except along the railroad 

 lines, hence it is a difficult area to study in detail. " The portion of this ter- 

 ritory to which attention is called lies in Marquette and Baraga counties, 

 and in this the following phenomena were noted and conclusions deduced: 



(1) Very light glaciation, especially light erosion, in all parts of the area, 

 and practically none in the high parts of the Laurentian highland in the 

 north half of Marquette county above 1800 feet a. t. In the vicinity of Mar- 

 cjuette there are excellent examples of glacial erosion imposed upon pre- 

 or inter-glacial weathering, without erasing it, while in the highlands north 

 of Michigamme, and both east and west of that point, recently uncovered 

 rock surfaces show no glacial smoothing or erosion. 



(2) On the north side of the Laurentian highland are three or four great 

 morainal terraces, made up of moraines and their accompanying out wash 

 plains. The latter rise quite to the level of the tops of the moraines, filling 

 in the space between the rock highland and moraines and giving the ter- 

 race form to the whole deposit. Above these, on the ancient rock peneplain 

 the till deposits are practically all in the form of valley moraines of very 

 small extent, or are wanting, while rock hills and valleys constitute the chief 

 topographic features. The valle3's contain gravel deposits or are partly 

 filled with great deposits of uneroded talus from the cliffs. 



(3) The south side of the highland westward from just west of Ishpeming, 

 along the D. S. S. and A. R. R., is marked by high, often precipitous cliffs, 

 banked against which is generally a thin deposit of till, covering, in some 

 cases at least, talus material. From this low bank, extending always south- 

 eastward, branch off a number of low moraines, which in places are so cov- 

 ered by forests and so closely related to lines of rock hills that it is often 



