62 JE. Orton — Occurren& of a Quarts JSoiolder 



Art. IX. — On the Occurrence of a Quartz Bowlder in the 

 Sharon Coal of Northeastern Ohio; by Edward Orton. 



It is well known that bowlders, ranging in size from a few 

 cubic inches to several cubic feet, are occasionally met with in 

 coal seams, buried partially or entirely in the substance of the 

 coal. Facts of this sort have been reported both in this country 

 and in England. The State of Ohio has furnished the largest 

 number, if not all, of the cases reported in this country. In 

 England, Mark Stirrup, Esq., Hon. Secretary of the Manchester 

 Geological Society, has reported in the Transactions of this 

 Society a number of such occurrences, all derived from mines 

 in the neighborhood of Manchester. 



The Ohio examples that have been hitherto put on record 

 are without exception, so far as my observation goes, composed 

 of gray quartzite, presenting the appearance of pretty thor- 

 oughly metamorphosed sandstones By correspondence and 

 comparison of specimens with Mr. Stirrup, I learn that the 

 English bowlders of the coal agree very closely with ours in 

 composition and general character. 



All of these bowlders are well rounded and some that I have 

 seen show remarkably smooth surfaces which suggest the pol- 

 ish due to glacier action rather than the abrading agency of 

 water in motion. They are always partially covered with 

 closely adhering coal, which shows more or less of the striated 

 structure known as slickensides. 



The Ohio bowlders have all been derived from a single coal 

 seam, viz : the Middle Kittanning seam of our scale, and thus 

 far, only from the western boundary of this seam, in Perry and 

 Vinton counties. Furthermore, a single mine in the last 

 named county, viz : the main mine at Zaleski, has furnished 

 thus far all the specimens. According to the testimony of the 

 superintendent and miners, scores of these bowlders have 

 sometimes been found in working out a single room. The 

 first example in Ohio was recorded by the late Prof. E. B. 

 Andrews (Geol. Survey of Ohio, Kept, of Progress, 1870, p. 

 78.) This bowlder came from the mine named above. 



By far the largest of this class of bowlders thus far known 

 was found buried in the coal of the same seams at Shawnee, 

 Perry Co., in 1876. The seam was normal above it and also 

 below. The weight of this bowlder is not less than 400 lbs. 

 It is preserved in the geological museum of the State Uni- 

 versity at Columbus. , 



A new example of these bowlders of the coal has lately been 

 brought to light that differs so much from the examples pre- 



