FILLMORE COUNTY. 283 



St. Lawrence limestone-] 







about twenty-five feet of regular beds, which have a fine even grain, and 

 though not plainly arenaceous, yet have a very fine grit. On fresh surfaces 

 it is of a buff color, varying to cream coloi 1 . The upper portion abounds in 

 patches of white calcite. There are also in the upper portion spots that 

 show thin, concentric, though wavy laminations, as if from concretionary 

 forces, or the result of silicified masses of foraminifers, reminding the ob- 

 server of the laminated masses of limestone from the Laurentian containing 

 the Eozoon Canadense of Dr. J. W. Dawson. Though the most of the rock 

 of this formation is vesicular, often coarsely so, it is much used for building, 

 for which it furnishes both large blocks for the heaviest masonry, and fine- 

 grained stone that can be cut into delicate forms. When cut for window 

 caps or sills the cut surfaces are nearly white. The bedding varies in 

 thickness from two or three inches to two or three feet, and sometimes 

 embraces thin beds of shaly, light-colored, fine-grained rock that is useless 

 for all purposes. 



At Clear Grit mills, in the valley of Root river, the St. Lawrence begins 

 to show a continuous line of bare rock, in the river bluffs, running along 

 the lower slopes, and causes a shoulder or terrace 'in the general descent. 

 A quarry near the mill-dam shows about fifteen feet of even layers. Above 

 these are the layers represented in the railroad cut near that place. These 

 are light-colored, dolomitic, vesicular, abounding in patches-of calcite with 

 some chert and siliceous concretions, the latter sometimes covered with 

 limonite, pseudomorphous after pyrite or marcasite. The annexed profile 

 exhibits the cut and the materials exposed. 



PIG. 16. RAILROAD CUT AT CLEAR GRIT. 



Explanation. 



a. Loess-loam, red 3 feet. 



i>. Drift-gravel, red 4 feet. 



c. Jordan sandstone, red 16 feet. 



d. St. Lawrence limestone - 30 feet. 



