SIBLEY AND NICOLLET COUNTIES, 1888. WARREN UPHAM. 



ness being perhaps 250 feet. This is the northern arm of the, anticline of which the 

 southern arm is seen in the quartzyte ridge of Watonwan and Cottonwood counties, 

 and its age is probably in the Keweenawan (Potsdam) but post-gabbro. 



The St. Lawrence limestone appears near the river at Hebron and Judson. It 

 is a rather thin-bedded and argillaceous dolomyte sprinkled with glauconite, and 

 interbedded with glauconitic sandstone. It also appears in Jessenland and in Faxon. 



The sandstone seen in Belgrade, Oshawa and at Mankato, underlying a heavy- 

 bedded magnesian limestone, comes next above the St. Lawrence limestone, and is 

 known as the Jordan sandstone. This is rather coarse grained, nearly white, hardly 

 ever fit for construction owing to its friable texture. 



But the overlying limestone, quarried at Mankato and St. Peter, as well as at 

 Belgrade and Kasota, is well known for its excellent qualities as a building material. 

 About forty feet of it are exposed in these counties. 



The Cretaceous is seen near Fort Ridgely, where it contains lignite, at and near 

 New Ulm, where it affords quicklime (Niobrara), and on section 16, Gourtland, where 

 it is a re-cemented quartzyte with fossil wood. N. H. w. 



