DODGE COUNTY. 373 



Galena limestone.] 



Section at Hook's quarry, Mantorvillr. 



1. Loose .fragments, 4ft. 



2. Beds from six to twenty inches each, of vesicular magnesian limestone, 



almost free from iron, very much used formerly for all kinds of construction, - 30 ft. 10 in. 



3. Thin, slaty, argillo-magnesian beds, 1 ft. 6 in. 



4. Good heavy beds of magnesian limestone, same as No. 2, - lift. 6 in. 



5. Shaly and thinner beds, seen. 5 ft, 

 NOTE Where these beds are weathered out, a white deposit is accumulated on the 



slope below, having much the taste of lime, yet it may consist of alumina and 

 lime. On the face of the rocks the coating is bitter and sour, tasting some- 

 what like Epsom salt. 



6. Heavy magnesian layers, of a buff color, with considerable shale - 20 ft. 



Total 63 ft. 10 in. 



The stone taken from the quarries at Mantorville is highly prized, and 

 has been placed in some important buildings.* It is evenly bedded and 

 can be got out in good shape. It has but little grit or flint to take off the 

 edge of tools, working easily and cheaply. It hardens after exposure, and 

 has a pleasant, light yellow color, or when from deep within the quarry 

 shows a light blue color. It is rarely affected by spots of iron pyrites. 



Section at Mantor's quarry. 



1 . Loose material, with broken rubble stone 2 ft. 



2. Light yellow rock, in layers three inches thick 1 ft. 



3. Yellow dolomitic rock, in thick beds 4 ft. 6 in 



4. Shaly, yellowish rock, including a layer of two inches of an uncemented, 



rather fine gravel containing numerous black quartzyte pebbles 6 in. 



5. Yellow, dolomitic rock, in thick beds 4 ft. 



Total "lifft" 



In the bed of the race at the second dam at Mantorville, a hundred 

 and ten rods below the mill, is a fossiliferous green shale. These sections, 

 and that which follows, show that the transition from the Trenton to the 

 Galena was gradual, the occurrence of the buff and magnesian layers mark- 

 ing those changes favorable for the deposition of the Galena limestone 

 which preceded the full introduction of that epoch. 



Section at Rockton mills, sec. 22, Mantorville. 



1 . Slope from the summit of the bluff (hid) estimated 40 ft. 



2. Magnesian layers, buff, much shattered 4 ft. 6 in. 



3. Shale : 2 ft. 6 in. 



4. Good layers of vesicular, buff, magnesian stone, with some argillaceous 

 patches. lift. 



o. Argillo-magnesian limestone, weathering into rather thin beds 3ft. 



6. Vesicular, buff, magnesian limestone. In one bed 10 in. 



7. Shale and shaly limestone 2 ft. 2 in. 



-'Compare the chapter on buiMing stones, p. 167. 



