HOUSTON COUNTY. 233 



Sand and calci te.] 



St. Lawrence stone is first taken out it cuts more easily than after exposure 

 for a few weeks, a fact which seems to be true of nearly all good building 

 stone. 



Sand. The St. Peter formation is excavated for mortar sand by Jesse 

 Scofield, sec. 14, Caledonia, and by John Burns on sec. 26. This white sand 

 is delivered at Caledonia village for $1.25 per load, or occasionally for $1.50. 



The St. Croix furnishes a similar sand near Mr. Kline's, sec. 16, Union. 

 These formations will supply a similar sand in any part of the county where 

 they are accessible. The layers in the St. Croix, however, are about two hun- 

 dred feet below the top of the formation. 



At Mr. Scofield's sand quarry, about a mile west of Caledonia, is a large 

 mass of lamellar calcite, lying on the slope of the St. Peter, and nearly 

 covered by the loam. In that respect it is like a similar mass seen near 

 St. Charles, in Winona county, in 1872, and mentioned in the report for that 

 year, but it seems more firm than that (see Winona county report). This 

 appears like a firm, very compact rock, consisting of almost pure carbonate 

 of lime, but somewhat colored. It is mainly massive, and striated or lami- 

 nated, but shows some crystalline grains. It weathers into undulating or 

 wavy smooth surfaces. There is another much larger mass, weighing many 

 tons, on 'the land of Mr. Willard, a short distance west. These masses can 

 be burnt into a purely white quicklime of great strength. 



The age and origin of this calcite are an interesting problem. When 

 that piece was found in Winona county, in 1872, it was referred hypotheti- 

 cally to the Trenton green shales, or to the worn-out Cretaceous that may 

 have covered that country, making it of rock origin, either Lower Silurian 

 or Mesozoic, but there is much reason to believe these calcite masses 

 are not referable to the rock in situ, but are of atmospheric origin, being 

 in short the remains of immense travertine deposits from limy water 

 running down the St. Peter slope from springs that once existed but are 

 now dry. They lie on the slope of the outcropping edge of the St. Peter, 

 just below the green shales which shed all the water that works down- 

 ward through any overlying limestone ; but they are also, so far as discov 

 ered, in regions where no overlying rock now exists, the only remaining 

 portion of the Trenton being that which lies below the green shales. This 

 is strikingly the case near Caledonia, where the Trenton is reduced to 



