414 THE GEOLOGY OF MINNESOTA. 



[Bricks. 



and one and a half miles south of Waterville, red brick have been made 

 during several years by Mr. David Wood, producing 200,000 to 300,000 

 annually, of excellent quality, bringing $7 to $8 per M. The clay used is 

 stratified. It contains no sand in its upper four or five feet; but its layers 

 below are separated by little seams of sand, occasionally with a thin film 

 of iron-rust. This clay-bed extends to a depth of at least 13 feet, and is 

 sufficient to make many millions of brick. 



A kiln of red bricks, inferior in quality because cracked after burning 

 by particles of limestone contained in the clay or sand used, was burned by 

 I. C. Trowbridge several years ago in Woodville beside the railroad one and 

 a half miles east of Waseca. No brick-making has since been undertaken 

 in that vicinity. Clay suitable for this use, having no gravel, is said to 

 occur on two or three acres of J. A. Canfield's laud in section 3, Otisco, at 

 about sixty rods northeast from his house. 



Springs, chalybeate and also supposed to be salty because licked by cattle, occur in section 9, 

 Otisco, south of the creek, being near the middle of the north side of the southwest quarter of this 

 section. Another irony spring, somewhat resorted to by the people of its vicinity and from 

 Waseca because of its medicinal properties, alterative and tonic, is situated northwest of the fore- 

 going, in the southeast quarter of section 5, Otisco. 



Aboriginal earthworks. The only mounds which seem to be perhaps artificial, observed or 

 heard of in Waseca county, are two or three low, circular and dome-like heaps of earth 20 or 30 

 feet in diameter but only one to two feet in bight, seen in and beside the road that runs from 

 Wilton southwest to Vivian, occurring nearly at the south line of section 10, and again in the 

 northeast quarter of section 20, Wilton. 



