1866.] MEETING OF AMERICAN ASSOCIATION. 121 



From the Minnesota at Redstone ferry west-ward, the 

 Cretaceous formation extends for forty miles unbroken, when we 

 come again to the red quartzites, which dip in the opposite 

 direction, or to the westward ; and continues for seventy miles, 

 coming out again at the Pipestone locality, on the Sioux valley. 

 At some point higher up the Minnesota valley, the Cretaceous 

 formation occupies large areas resting on Laurentian rocks. 



The result of these investigations shows a portion of the outcrop 

 of a synclinal axis on the east of the Minnesota, with a valley of 

 forty miles in width, which has been eroded in the line of a great 

 anticlinal axis ; while beyond this is a synclinal axis ; of quartziteF, 

 of similar character, which forms the foundation of the great 

 Coteau-des-Prairies, which extends for more than four hundred 

 miles to the northwest, rising seven or eight hundred feet above 

 the lower prairie. 



"We have the evidence that the synclinal axis referred to is the 

 highest portion of the country, while the anticlinal axis had been 

 eroded prior to the age of the Triassic formation. 



The chains of lakes of this part of the country, lie in the 

 plateau of the synclinal axis, while the line of the anticlinal is 

 free from this feature ; and the same conditions, essentially, 

 prevail in a portion of a more eastern synclinal, which lies to the 

 east of the Minnesota River. 



ON PETROLEUM. 



At the opening of the session, Dr. T. Sterry Hunt read an 

 interesting paper on Petroleum, of which the following is a brief 

 synopsis. 



He had shown in 1861, that the mineral oil of Western Canada 

 was indigenous in the Corniferous limestone ; wells sunk in the 

 outcrop of which have yielded, and still yield, oil in that region, 

 and also in Kentucky, according to Lesley. At that time (1861) 

 he called attention to the existence of petroleum in the limestones 

 of the Trenton group, and had, since then, in the Geology of 

 Canada, in 1863, insisted upon these Lower Silurian oils as likely 

 to prove, in some regions, of economic importance — a prediction 

 verified by the recent developments in the Lower Silurian strata 

 of the Cumberland, in Kentucky, and the oil wells of the Mani- 

 toulin Islands, which latter are sunk through the Utica into the 

 Trenton formation. Another important point, on which he had 



