640 GEOLOGY or OHIO. 



road crosses Black Lick. The stoae has been quite extensively worked 

 here. It can also be seen in various neighborhood quarries in Plain and 

 Mifflin townships in the banks of Rocky Fork and Big Walnut Creeks. 

 The Black Lick section is much heavier than either of th'e others, and 

 will alone be considered here. 



It measures forty-eight feet. Its lowest bed belongs to the Waverly 

 shales, but this course is seldom reached in the operations of quarrying. 

 The annexed wood cut gives the divisions of the system as it is here 

 exhibited. It will be seen that the courses marked as valuable are 

 quite widely separated and constitute but a small proportion of the 

 quarry. Only those courses that furnish stone in blocks adapted to cut- 

 ting have been thus designated. Much of the remainder furnishes 

 building stone, the quality of which is quite equal to the cutting stone, 

 excepting only in the size of the blocks in which it is raised. The 

 waste, however, is considerable. It includes concretionary masses in 

 which no bed lines can be seen, but which look like masses of mud to 

 which a rolling motion had been given before they were solidified. 

 These courses are most numerous near the bottom of the system, and 

 are characteristic of the lower Waverly throughout central and southern 

 Ohio. Some of the best cutting stone is found in portions of the courses 

 that are marked concretionary. Their courses of shale contribute also 

 to the waste, but the largest element is thin-bedded sandstone that has 

 little strength and as little durability. It is light yellowish in color. The 

 layers are from one to four inches in thickness. The presence of so 

 much useless material would render the quarrying quite expensive if it 

 were carried on to any great extent. 



The best of the courses are, in color, light blue, and quite uniform in 

 texture, and work well under the saw. The Ohio Institution for the 

 Blind is built of stone from these qimrries. The foundations of the 

 Union Depot at Columbus were also supplied from Black Lick, as well 

 as several fronts of newer blocks in the city. Like the rest of the lower 

 Waverly, these quarries furnish some unreliable stone distributed through 

 the best of courses. No selection is possible in the process of quarrying 

 by which the perishable portions can be separated from the more durable. 

 The element of time must necessarily come in, and the stone should 

 never be laid until the quarry water has all escaped, for the exfoliation, 

 which disfigures the surface of these treacherous portions, is generally 

 connected with the escape of this quarry water. The Waverly of cen- 

 tral and southern Ohio is less silicious in composition than the northern 

 Ohio stone of the same age, and it is in connection with the aluminous 

 constituents which replace a part of the sand that this uncertainty of 

 quality comes in. 



