464 REPORT OF NATIONAL HUSEUM, 1899. 



those stones that have originated as sandy deposits on sea bottoms and 

 have undergone little if any metamorphism in other words, in sand- 

 stones. For some particular reason, or rather owing to certain 

 peculiar conditions, although sandstones were formed throughout a 

 great number of periods in the earth's history, those formed during 

 the Carboniferous age seem best adapted for the purpose, and from 

 stone found somewhere in this formation are manufactured a large 

 share of the grindstones now in use. 



A majority of the grindstones now found in the markets of the 

 United States are made from sandstones quarried from the Upper, Mid- 

 dle, and Lower Carboniferous formations of Ohio, Michigan, Nova 

 Scotia, or New Brunswick, or England and Scotland. A few are, or 

 have been, made from stone from Missouri and Kentucky. The Ohio 

 stones are obtained nearly altogether from quarries in the sub-Car- 

 boniferous sandstones at or near Berea, Amherst, Bedford, Constitu- 

 tion, Massillon, Marietta, Independence, and Euclid. Few if any of the 

 quarries are worked wholly for grindstones, but in the majority of 

 cases the stone is sought for building purposes as well, and the grind- 

 stone output may be merely incidental, certain layers only being 

 adapted for the latter purpose. This is well illustrated by the following 

 section, as shown at one of the Amherst quarries and as described 1 by 

 Professor Orton, the State geologist. The reader will understand that 

 by section is meant the various layers exposed in the quarry wall, or 

 that would be passed through in digging or boring from the surface 

 downward. 



At Amherst, then, the stone lies as follows, beginning at the surface: 



Feet. 



Drift material (soil, sand, etc.) 1 to 3 



Worthless shell rock 6 to 10 



Soft rock used only for grindstones 12 



Building stone 3 



Bridge stone 2 



Grindstone 2 



Building and grindstone 10 



Building stone 4to 7 



Building stone or grindstone 12 



Commenting on the condition of affairs as here displayed, Professor 

 Orton says: 



As will be noticed in this section, the different strata are not applicable alike to 

 the same purpose, and the uses for which the different grades of material can be 

 employed depend principally upon the texture and the hardness of the stone. The 

 softest and most uniform in texture is especially applicable for certain kinds of grind- 

 ing, and is used for grindstones only, and the production of these forms an important 

 part of the quarry industry. In its different varieties the material is applicable to all 

 kinds of grinding, and stones made from it are not only sold throughout this coun- 



1 Geological Survey of Ohio, V, p. 586. 



