140 NINTH REPORT. 



600- 700 feet above sea level 



700- 800 " 



800- 900 " 



900-1000 " 



1000-1100 " 



1100-1200 " 



' 1200-1300 " 



1300-1400 " 



1400-1710 " 



The most remarkable feature indicated by this table is the plateau forma- 

 tion above the 1100-foot contour line which embraces the greatest part of 

 the upper portion of the Lower Peninsula. 



The average elevation for bed rock of Lower Michigan as determined 

 from Plate II of the report referred to above is 554 feet above sea level, mak- 

 ing the average thickness of the soil and subsoil formation, properly known 

 as the drift, aj^proximately 300 feet for Lower Michigan. There is consider- 

 able margin for error here, but all knowledge is progressive and beginnings 

 are to be taken in the proper spirit. In Bay county we have an average 

 thickness of the drift of 97 feet as determined from 460 drill holes for coal 

 and 126 well records.^ 



Probably the highest elevation in Upper Michigan is Mt. Whitney in the 

 Porcupine Mountains, and not far from Ontonagon, which has a height of 

 2023 feet above sea level, and this is probably the highest altitude in the 

 .state. 



In the Lower Peninsula we have two areas of topographic development, 

 which are clearly the result of former geological conditions. In the central 

 part of the state we have the Saginaw-Maple-Grand valley. South of this 

 in the Hillsdale uplands we have the highest elevation south of the latitude 

 of Saginaw Bay, this portion of the state culminating at Bunday Hill, where 

 the elevation is 1284 feet above tide. North of this area, southeast of 

 Cadillac, and in the north central part of Osceola county, the land reaches 

 an altitude of 1710 feet above sea level, which I am told is the highest ele- 

 vation in Lower Michigan. It is, moreover, worthy of note that both the 

 elevation of the bed rock and the present land surface vary approximately 

 1100 feet in extremes of elevation in this portion of Michigan, indicating 

 a certain amount of uniformity in topographic developments and the result- 

 ants of agencies during glacial and earlier geological periods. 



In the report on the "Geology of Bay County," the former drainage sys- 

 tem of the state, which was in the course of development after the elevation 

 of Michigan above the sea at about the close of the Paleozoic, was given spe- 

 cific designations in the same manner that our present drainage system is 

 designated. 2 The advantage of this plan is in convenience and definite- 

 ness of arrangement and designation, while on the other hand we are able 

 to reconstruct the former physical geography of the Lower Peninsula, in a 

 manner consistent with the present, thereby giving life and unity to long 

 bygone times. 



During this former age of topographic development during Mesozoic and 

 Cenozoic times the drainage in central Michigan was westward, probably 

 through the southern part of Bay and Midland counties, the northern part 



1 W. F. Cooper, Bay Co., Ann. Rep. Geol. Surv. of Mich, for 1905, p. 339. 



2 Geology, Bay Co., Ann. Rep. Mich. Geol. Sury., 1905, pp. 162-165 and 333-339. 



