ANTICLINE IN CHAGRIN SHALES, CLEVELAND 771 



LOCAL ANTICLINES IN THE CHAGRIN SHALES AT CLEVELAND, OHIO 

 BY FEANK B. VAN HORN 



(Abstract) 



CONTENTS 



Page 



Introduction and local geology 771 



Description of the anticlines 771 



Probable causes of the flexures 771 



Conclusion 772 



Introduction and local Geology 



In April, 1909, operations were begun in the eastern limits of Cleveland on 

 the construction of the new Belt Line Railroad. Its tracks lie beside those of 

 the New York, Chicago and Saint Louis Railroad for several miles, and both 

 roads agreed to abolish many grade crossings. Their plans called for an ex- 

 cavation wide enough for four tracks between Cedar Avenue and Mayfield 

 Road, a distance of nearly a mile. The cut is from 10 to 20 feet deep and the 

 material consists of from 2 to 3 feet of glacial drift, mostly sand and gravel, 

 while the remainder is Chagrin (formerly called Erie) shale. This is of 

 upper Devonian age stnd is quite thinly bedded. At the surface the shale is 

 invariably yellow from the formation of limonite, but below the line of normal 

 weathering it possesses a slate blue color. The shale often contains concre- 

 tionary masses known as clay ironstone, as well as masses of iron sulfide, 

 generally in the form of pyrite, although marcasite may sometimes be present. 

 It seems probable that the nucleus of the ironstone masses is also iron sulfide. 

 When exposed to the air the shale, although originally often very hard, disin- 

 tegrates rapidly into a tough, plastic clay, and is used quite extensively around 

 Cleveland for the manufacture of vitrified brick and paving blocks. At times 

 the shale contains sandstone layers which vary both as to their number and 

 thickness. 



Description of the Anticlines 



Along the banks of this newly excavated cut many anticlinal folds were ob- 

 served, particularly between Cornell and Mayfield Roads on the east and 

 between Adelbert Road and Cedar Avenue on the west. The flexures were 

 generally unsymmetrical, with limbs varying from 3 to 10 feet in length. In 

 one case a monocline was noticed, but with this exception all folds belonged to 

 the anticlinal type, no synclines being observed. The disturbance of the strata 

 never extended more than 15 feet below the surface, and always passed into 

 horizontal shale at the bottom and sides of the anticlines. Furthermore, the 

 movement never, except in one case, extended to the opposite side of the cut. 

 This shows that the anticlinal axis pitched rapidly and disappeared in the 

 horizontal shale. In the one exception just mentioned the limbs of the folds 

 on the opposite sides of the cut had no apparent relation to each other, except 

 that a disturbance of the shale took place along the same general axis. 



Probable Causes of the Flexures 



The general observations mentioned previously indicate that the anticlines 

 were always of local origin, and that the direction of motion was vertically 



