Nov., 1917] Concretionary Forms 7 



There is need of studying, in this connection, the behavior of 

 microorganisms near the equator as well as in the southern 

 hemisphere, particularly in an experimental way, before definite 

 conclusions may be drawn. 



Kcnyon College, Gambicr, O., Oct. 15, 1917. 



CONCRETIONARY FORMS IN THE GREENFIELD 



LIMESTONE.* 



Charles W. N.'Xpper, Greenfield, Ohio. 



The locality of this study is at Greenfield, in southwestern 

 Ohio. The workings are the Rucker Quarries. The rock is a 

 Silurian dolomite, the quarry face above and below water-level 

 measuring sixty (GO) feet. Characteristic features divide the 

 exposure into two parts, called the Gray Stone for the lower 

 twenty(20) feet and the Buff Stone for the upper forty (40) 

 feet. 



In this paper the term "concretionary force" is employed 

 in the sense and with the idea of the aggregation of rock material 

 into various forms which are distinctly different from the 

 surrounding stratification. 



THE GRAY STONE — THE ISOLITH. 



Herein the concretionary force is manifested in one single 

 form. This stone is very evenly bedded, the ledges maintaining 

 horizontal regularity unless there is interference from large, 

 irregular, unstratified masses over which they bend. 



The quarrymen call these masses "horsebacks" or "blisters" 

 and this has caused the writer to search for possibly a better 

 name. While producing a disturbance somewhat similar, 

 the terms laccolith and bathoUth can not be used for they refer 

 to conditions produced by the intrusion of one kind of rock, 

 igneous, into another, hence two kinds of rock material are 

 involved. In our instance, the masses causing disturbance 

 and the strata disturbed are of one and the same rock material. 

 Therefore I suggest and have used the term "isolith" for them. 



*This paper, accompanied by lantern slide views and an exhibit of forms 

 described, read before the Geological Section of the Ohio Academy of Science,, 

 meeting in Columbus, at the Ohio State University, April 7, 1917. 



