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The Ohio Journal of Science [Vol. XVII, No. 5, 



the Scioto, where it runs eastward, west of Columbus. Four 

 or five more newer and much larger ones are located just north 

 of the Marble Cliff bend; and then a series of lesser quarries, 

 some old and some new, occupy favorable sites from these 

 larger ones northward even to the northern boundary of the 

 area. Not only have the streams carved deep cuts into the 

 rock and thus accomplished all the preliminary work of opening, 

 but they have cut so deeply that large quarries can be worked 

 above river level with no fear of water to trouble the workmen. 



Fig. 6. Drain tile plant situated near Black Lick, because the soft Bedford shales 



are here available. 



Another item which makes quarrying easy is the fact that the 

 glacier, scouring over this region removed nearly all partly 

 decayed rock, leaving the fresh solid limestone, shales and 

 sandstones at the surface; and again as the larger streams have 

 made their valleys they have removed nearly all drift that the 

 glaciers left, on these future quarry slopes. 



In the northwest portion of the area preglacial interstream 

 ridges of limestone are so thinly mantled, and so thoroughly 

 cleared by the glaciers of their partly weathered rock, that 

 quarries have been opened in them without the aid of the rivers. 



Just as the streams and glaciers have prepared easy quarrying 

 of the limestones in the western half, so in the eastern half of 



