Suburban Geology of Richmond, Indiana. 297 



upper stratum of rock, and appears to have erased the litho- 

 graphic furrows, for the surface is undulating, and the depressions 

 are as smooth as the elevations : whether these portions of the 

 rock were ever scratched, I will not pretend to say; but they 

 now have every appearance of water-worn rocks. The con tin- 



4 



uation of the same layer a few yards distant from these places, 

 exhibits the veritable grooves, varying from a mere scratch to 

 furrows an inch or more wide, and with one or two exceptions, 

 running exactly parallel with each other. The average depth 

 of these grooves is perhaps an eighth of an inch, and their breadth 

 and shallowness give to the surface of the rock a vitiated appear- 

 ance. This surface in every instance is whitened by the pow- 

 der of the scraped rock, and the powder being impalpable, renders 

 the surface smooth to the touch, like that of soapstone. All these 

 effects denote clearly the nature of the cause, which has left to 

 us this hoary memorial of its action. 



It is observable that the direction of these markings does not 

 accord with the general course of such as are found elsewhere in 

 the United States. The following references (all I can at present 

 command) exhibit a very striking deviation from the course of 

 the grooves, reported in the several instances cited. 



1. Primitive rocks of Maine, (Jackson,) N. 15° to 20° W. 



2. Greenstone, New Jersey, (Rogers,) N. 45° W. 



3. Trenton limestone, N. Y., (Emmons,) N. 25° to 48° W. 



4. Ripple marks, N. Y., indicate a force from N. 30° W. 



5. Cliff rock, near Dayton, O., (Locke,) N. 26° W. 



6. Blue limestone, Richmond, Ind., (Plummer,) N. 20° East. 



In the above table, 1 have designated the direction of the mark- 

 ings in accordance with the supposition, that the impulse causing 

 the motion was from the north. But however strong the evi- 

 dence may be that bowlders, &c. have been swept southwardly, 

 I do not consider it conclusive that the same force abraded the 

 rocks. On the contrary, may I presume to say, indications ap- 

 pear to contradict the supposition. And I will risk my claims to 

 sagacity still farther, by stating that neither the iceberg theory, 

 the glacial theory, nor any other that I have studied, appears to 

 be sufficient to account for the phenomenon in question ; and 

 that it has for a long time been an interesting question with me, 

 whether, in the upheavings and tiltings of the various forma- 

 tions, the strata have not, in the places of " diluviaV^ scratches, 



Vol. xnv, No. 2.— Jan .-March, 1843. 



38 



