150 THE GEOLOGY OF MINNESOTA. 



[Red Quanzyte. 



color being due to iron oxide which is disseminated among the grains 

 and throughout their cement. As a layer embraced in this rock, the mate- 

 rial known as "red pipestone", or catlinite, is found in Pipestone county and 

 other places in southwestern Minnesota. This rock is very difficult and 

 costly to dress into dimension blocks, but it is indestructible when once 

 placed in a wall. 



The quarry at Redstone, near New Ulm, was opened in 1859 by Nicholas 

 Thinnes, but since then several other parties have done most of the quar- 

 rying, none of it, however, in a systematic manner. The quarries are con- 

 tiguous and exhibit the same kind of rock. Much of that which is used now 

 is thin-bedded, from one-half inch to two inches thick, but the stone could 

 be got of any size and thickness desired. The layers dip about 15 degrees 

 toward the N. N. W. As compared with the rock at Sioux Falls, the oppor- 

 tunities here for quarrying are greater, and the stone is much more easily 

 wrought. Its bedding is thinner and softer, though it is likely that by exra- 

 vating deeply these beds would be found to be firm and purplish within. 

 Some of the stone is wholly disintegrated, or loosened so as to be a sand- 

 rock, losing its color to the depth of 2 8 feet, and some beds are loose- 

 grained. Some of the lower beds are syenitic.* 



' Samples of the Redstone rock in construction can be seen in Sommers' 

 block and Frank Erd's residence, both at New Ulm, and also in the basement 

 of the Catholic church at the same place. 



In Cottonwood county an extensive ridge of this rock, mainly covered 

 by the glacial drift, runs east and west through Storden, Amboy, Delton 

 and Selma townships, and enters Adrian in Watonwan county. Along 

 the branches of Mound creek in Amboy and in Germantown, are fre- 

 quent and favorable exposures. On the Little Cottonwood river are excel- 

 lent opportunities for quarrying flagging; some pieces loosened by the 

 action of the water being five or six feet long by three to five feet 

 wide, and three or four inches thick. Many pieces much thinner are also 

 found. Outcrops of the quartzyte occur frequently along the summit and on 

 both slopes of this ridge, even where there is no water-course. The rock 

 here has mostly a reddish gray color. Its stratification is in some places 

 nearly horizontal, but more commonly it dips several degrees, often toward 



See the first annual report, p. 75. 



