Notice of Geological Surveys. 131 



cylinders, fonr inches in diameter, — Madrepores in hemispheres 

 three feet over, associated with Encrini an inch in diameter, and 

 much larger than those in the blue. The blue contains Ortho- 

 ceratites, and the- fragments of large trilobites, one of which, 

 called "Isotelus maximus," is figured as reconstructed from the 

 proportions of the fragments, and is twenty one inches long. 

 These strata are nearly horizontal, having a prevalent dip of north 

 fourteen degrees east, and about six feet in a mile. 



Large areas of this rock being uncovered for the purpose of 

 quarrying, it is found planished as if by the friction of some 

 heavy body moving over it, and marked by parallel grooves, 

 which are regarded by Dr. Locke as " diluvial scratches ;" they 

 are found at " Light's quarry, east of the Miami, and seven miles 

 above Dayton, thus rendered particularly interesting by the dis- 

 covery in it of ' diluvial grooves,' a circumstance which I had 

 thought probable from the fact of the planishing or grinding 

 down of the strata" first observed at Col. Partridge's quarry, 

 " where the upper surface, especially at the apex of its convexity, 

 has its roughness nearly worn oif, not by corrosion or by decom- 

 position, nor by the attrition of sand and gravel, but by the grind- 

 ing of a fiat surface, making the work, so far as it went, a perfect 

 plane, and leaving the pits of the deepest cavities entirely un- 

 touched."* " Light's quarry has been ' stripped' of soil, more or 

 less, over ten acres, and the upper layer of stone is in most places 

 completely ground down to a plane, as perfectly as it could have 

 been by a stone-cutter by polishing." " In many places, grooves 

 and scratches in straight and parallel lines, are distinctly visible, 

 evidently formed by the progress of some heavy mass, propelled 

 by a regular and uniform motion. The grooves are in width 

 from lines scarcely visible, to those three fourths of an inch 

 wide, and from one fortieth to one eighth of an inch deep, travers- 

 ing the quarry from between north 19°, to north 33° west, to the 

 opposite points in lines exactly straight, and in fascicles of some- 

 times ten in number, exactly parallel ; clearly in compact lime- 

 stone, without seam or fault of any kind — and in a surface ground 

 down to a perfect plane." To illustrate these appearances, a por- 



* These cavities are found, where another layer of the rock lies upon this, to an- 

 swer to salient points in the upper one, and the " natural surface of the stone is 

 within certain limits as rough as can be conceived, there being sharp teeth, an inch 

 long, projecting from one layer and entering the contiguous one." 



