AMERICAN GEOLOGISTS AND NATURALISTS, 43 



Monday^ April 25th, 3 J o'clock, p. i\i., Prof. Locke in the chair. 



Prof. Locke exhibited sections of the rocks of the lead regions 

 of the Upper JVIississippi, with remarks on the geology of the 

 West. 



Prof. L. proceeded to state as follows : — I present to-day some 

 geological sections of the lead region of the Upper Mississippi. 

 These were made by myself during the survey of the Mineral 

 Lands, ordered by Congress, and by Dr. Owen and myself with 

 numerous assistants in 1839. A detailed report of that survey was 

 made to the Department of the Land Ofhce early in 1840, but owing 

 to some mismanagement at Washington, it was published without 

 the illustrations, which were numerous, and so connected with the 

 text that the document became nearly unintelligible without them. 

 As this paper, imperfect as it is, has been seen by few of our geolo- 

 gists, and as the sections before us are chiefly in connection with 

 what I have denominated the cliiT limestone of the West, I will ask 

 leave to read from my printed report some remarks upon that rock. 

 This I do more especially, as it appears not to be known or recollect- 

 ed that I have a claim to the discovery that the metalliferous rock 

 of the Mississippi is identical with the cliff limestone of Ohio, and 

 that the same rock, wherever it has been found, is more or less met- 

 alliferous. [Here was read part of the Pteport of Prof. L. to Dr. 

 Owen, referred to as published in Document 239, 26th Congress, 

 United States. — The following sections were also exhibited and 

 explained.] 



" I. A section from the heights of Little Mahoqueta through Du- 

 buque Mines to Sinsiuawa Mound, fifteen miles. This section ex- 

 hibited, 



1. The cliff limestone, containing in its middle and lower portions 

 the lead veins. 



2. The blue limestone, (Trenton limestone.) 



3. Presumptively, the lower magnesian underlying the blue. 



" II. A section at Prairie du Cliien, exhibiting the following rocks, 

 descending series : 



1. Soil and clitf limestone, . . - . . 



2. Blue fossiliferous limestone, - . . . 



3. BufF colored limestone, . . - . . 



4. Soft saccharoid sandstone, - . . - . 



5. A portion covered by soil, . - . . - 



6. Lower magnesian limestone resembling the cliff, litho- 



logically, but nearly destitute of fossils, 



7. Saccharoid sandstone, ..... 



This last is exposed only at low water. 



Total, 495 feet. 



" III. A section from Blue Mounds to Wiskonsin River, exhibit- 

 ing the following descending series of rocks : 



