BUILDING STONES. 171 



Limestones.] 



zontal strata, and is exposed along the railroad cut east of the village. It 

 is stratigraphically the equivalent of the beds quarried more extensively at 

 St. Paul and Minneapolis, but the stone differs from the latter in being 

 nearly free from shaly impurities. It is of a drab color, but passes to a 

 bluish color on being opened more deeply, and has a very compact or dense 

 texture. There are here beds of shale, but they are distinct from the lime- 

 stone beds. They facilitate the operations of the quarrymen, but do not 

 impair the quality of the rock. In quarrying the layers rarely exceed five 

 inches in thickness. On the weathered bluff they appear even thinner 

 than that, being apparently not more than two inches. They are tough 

 and hard, and when broken they often fracture chonchoidally and in unex- 

 pected directions. The same kind of stone is quarried at Chatfield, in the 

 upper bluffs, also near Faribault and Northfield, both in Rice county. In 

 passing northward, however, and thus approaching the old shore-line of the 

 paheozoic ocean, more argillaceous shale is found mingled with the rock; 

 so that, even in those comparatively quiet times, when marine animals 

 flourished and on their death supplied a calcareous deposit, there was pres- 

 ent so much shaly (or clayey) sediment that the resulting rock is not so pure a 

 limestone as further south. At the southern points the quiet, lime-producing 

 epochs were less characterized by this impurity, but were separated more 

 distinctly by periods of agitation when large amounts of shale were depos- 

 ited. Hence in this formation at Minneapolis and St. Paul the argillaceous 

 ingredient is distributed with the calcareous and also constitutes heavy beds 

 of itself; while, at Northfield and F.aribault, the calcareous layers are more 

 nearly pure, and at Fountain are almost free from alumina and silica. At 

 the same time in passing toward the south the purely argillaceous beds 

 become thicker as the calcareous become thinner. This is unfortunate for 

 the cities of Minneapolis and St. Paul which have to depend very largely on 

 the Trenton limestone for building material, or to import from other places, 

 but it is fortunate for those towns in the southern portion of the state which 

 have to use the same strata. 



The quarries near Faribault are in the town of Cannon City, about two 

 miles east of Faribault. A small creek (Fall creek) here unites with the 

 Straight river at its northern bend, and in its bed and along its bottoms 

 the strata appear in a horizontal position. The quarry, owned by Philip 



