330 TRANS. OF THE ACAD. OP SCIENCE. 



quite common, and the layers are sometimes concretionary. 

 The ironstone concretions are sometimes beautifully divided 

 by small calcareous veins passing perpendicularly to the 

 concentric circles forming "septaria;" these varying in 

 size from one inch to four feet. 



Fossils are exceedingly rare ; in the thinly laminated 

 beds adjacent to and interstratified with the coal, they some- 

 times abound. The shale beds intercalated with the coal 

 in Andrew County, near Eochester, abound in beautiful 

 fossil plants. When the shales are calcareous they often 

 abound in Brachiopoda. 



Limestones. — The gray and buif limestones are better than 

 the blue for most purposes, being purer, firmer and more easi- 

 ly worked. They are good for building and for making lime, 

 and withstand fire better. The blue limestones, especially 

 the ashy-blue, are generally pyritiferous, and when contain- 

 ing iron pyrites, oxidize with a thick brown crust on the 

 exposed surfaces. The beds are generally jointed by ver- 

 tical planes passing through and forming regular rhomboid 

 blocks ; when the upper surface is much exposed, an ap- 

 pearance is often presented as of a floor paved with lozenge- 

 shaped flagstones. This character belongs sometimes to 

 the buff limestones, and is more common in the lower series. 



Some fossils seem to be peculiar to the blue limestones, 

 and Lamellibranchs and Gasteropods are more often asso- 

 ciated together. Leptodomus and Edmondia are more often 

 associated in the blue limestones and occur but seldom any- 

 where else. Allorisma is also more common. Brachiopods 

 are more characteristic of the gray limestones, Lamelli- 

 branchiata and Gasteropoda of the blue. 



Coal. — The following is the boundary of the Coal Meas- 

 ures in North Missouri, giving the principal points, it vary- 

 ing often for several miles either way : 



Crossing the Missouri above Arrow Rock, thence via 

 Boonslick, Columbia, New Bloomfield, Fulton, Wellsville, 

 near Montgomery City, Middleton, near Vannoy's Mill, 

 Lick Creek, Santa Fe, Mexico, Middlegrove, Madison, N.W. 

 corner of Monroe County, Lakenan, Kirksville, and north- 

 wardly; with patches and outliers in Monroe, Marion and 

 Shelby. If we trace an imaginary line from Lexington via 

 Utica, thence N.E. to the N.E. part of Sullivan County, and 

 northwardly to the State line, we have on the east the 

 workable coal beds, and to the west 1,450 feet of unproduc- 

 tive coal measure rocks; for the beds of coal in the upper 

 measures are too thin to admit of working to any advan- 

 tage, and only when situated in remote districts where 

 wood is scarce and transportation expensive, will it pay to 

 work them. 



