Associaiio7i of Atnerican Geologists a7id Naturalists. 147 



Provided only, that in all cases where the paper is to be with- 

 drawn, as above, there shall be no discussion on the subject. 



The Association then adjourned until 3J o'clock, P. M. 



Monday, April 25th, 3 J o'clock, P.M. — Prof. Locke in the chair. 



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

 of the Upper Mississippi, with remarks on the geology of the west. 



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

 logical 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 assist- 

 ants in 1839. A detailed report of that survey was made to the 

 Department of the Land Office early in 1840, but owing to some mis- 

 management at Washington, it was published without the illustrations, 

 which were numerous, and so connected with the text that the docu- 

 ment became nearly unintelligible without them. As this paper, imper- 

 fect as it is, has been seen by few of our geologists, and as the sections 

 before us are chiefly in connection with what I have denominated the 

 cliff limestone of the west, I Avill 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 recollected that I have a claim to the dis- 

 covery 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 metalliferous. [Here was read part of the 

 report 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 Dubuque 

 Mines to Sinsinawa Mound, fifteen miles. This section exhibited, 



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 Chien exhibiting the following rocks, 

 descending series : 



1. Soil and cliff limestone, ..... 60 feet. 



2. Blue fossiliferous limestone, - - - - - 115 " 



3. Buff colored limestone, - - - - - 20 " 



4. Soft saccharoid sandstone, - - - - - 40 " 



5. A portion covered by soil, - - - - - 40 " 



6. Lower magnesian limestone resembling the cliff litholo- 



gically, but is nearly destitute of fossils, - - 190 " 



7. Saccharoid sandstone, - - - - - - 30 " 



This last is exposed only at low water. 



Total, 495 feet. 



