16 EEPORT OF THE 



Lands," was submitted as Part I., on the 15th of April, 1850.* 

 Part II., on the " Iron Region" and General Geology, was sub- 

 mitted November 12th, 1851, and forms a volume of 406 pages 

 and XXXV. Plates.f Messrs. Poster and Whitney were aided 

 in the field work of the survey by Messrs. S. W. Hill and 

 Edward Desor as first assistants ; by Mr. William Schlater as 

 Draughtsman, and Mr. W. D. Whitney as Botanist. The fossil- 

 iferous region was also passed over by Prof. James Hall, the 

 paleontologist of New York, whose observations and general 

 conclusions are embodied in the Report, together with papers on 

 the Geology of Wisconsin, by Dr. I. A. Lapham, and Col. Chas. 

 Whittlesey. The latter also communicated important chapters 

 on the " observed fluctuations of the^surfaces of the Lakes," and 

 "magnetic variations," with a "comparison of terrestrial and 

 astronomical measurements.'' 



The examinations reported upon in Part II., extended around 

 the entire Lake shores of the Upper Peninsula, as far as the 

 head of Green Bay, and embraced the islands at the head of Lake 

 Huron, from Mackinac to Drummond's Island. The groups of 

 of rocks observed wore found to conform to the geology of New 

 York and other States, and a parallelism was established, from 

 the Potsdam Sandstone to the Upper Helderberg Group. 



No further public geological explorations were made with- 

 in the limits of our State, until the commencement of the 

 present survey. The mining companies of Lake Superior, how- 

 ever, maintained a series of local explorations, which have con- 

 tributed a vast amount of detailed information, destined to be 

 of the greatest service in the compilation of a general report. 



During the legislative session of 1858, numerous petitions 

 were presented for' the completion of the geological survey of 

 the State. The number was greatly increased at the session of 

 1859, and, although the condition of the State Treasury was re- 

 ported to be such as hardly to justify embarkation upon any ex- 

 traordinary expenditures, it was finally deemed advisable to make 



*Executive Dop. No. 69, 1st Sess. 31st Cong., Vol. 9, 1849-50. 

 fEsecative Doo. No. 4, Special Sess. 32d Cong., Vol. 3, 1851. 



