SILURIAN FOSSILS FROM OHIO, WITH NOTES ON 

 RELATED SPECIES FROM OTHER HORIZONS. 



Aug. F. Foerste. 



The term West Union Cliff was proposed by Prof. Edward 

 Orton in the Report of Progress in 1870, published by the 

 Geological Survey of Ohio in 1871. On page 274 of this report 

 he states that this formation "can be studied to excellent 

 advantage in the typical section of Bisher's dam, where it 

 forms the first line of cHffs in ascending the hill. At this 

 point, it measures 45 feet. To the southward, it is reinforced. 

 It is Dr. Locke's 'Cliff limestone,' of Adams county — to which 

 he assigns a thickness of 89 feet at West Union." It should 

 be noted that although the nanie of the formation is chosen 

 from West Union, that no description of the West Union section 

 is given; Bisher's dam is regarded as offering the typical section, 

 but no detailed description of the Bisher's dam section is given,, 

 beyond the general statement that near Hillsboro it consists 

 of a yellowish, impure magnesian limestone, and that the stone 

 is rather massive than even-bedded in its appearance. Bisher's. 

 dam is about a mile south of Hillsboro. 



The overlying rock, or Upper Cliff, was called by Orton the 

 Blue Cliff. The best exposures of the Blue Cliff are stated to 

 be at Hillsboro, along the abandoned line of the Cincinnati 

 and Hillsboro railroad, at Academy Hill and at the Trimble 

 quarry at the eastern end of the railroad cut at the eastern 

 margin of the city of Hillsboro. The prevailing color is blue, 

 weathering into various shades of drab and buff. The thickness 

 of the Blue Cliff proper is from 20 to 30 feet ; it is underlaid by 

 5 to 15 feet of blue shale or soapstone, producing a maximum 

 thickness of 30 plus 15, or 45 feet. The basal part of the Blue 

 Cliff proper generally consists of quite massive limestone 

 courses, often more or less crinoidal. The Blue Cliff was 

 incorrectly identified by Prof. Orton with the Springfield 

 dolomite of the more northern counties of Ohio. 



Those Niagaran limestones which lie above the Blue Cliff 

 in the Highland county areas, especially at Hillsboro, were 

 correlated by Prof. Orton with the Guelph of New York and 



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