GEOLOGY. 249 



ON THE EXISTENCE OF DILUVIAL AGENCIES DURING THE EARLIER GEO- 

 LOGICAL PERIODS. 



THE following is an abstract of a paper, read at the American Asso- 

 ciation, Albany, by Dr. F. M. Hough : 



The abrading and polishing action of moving masses of rock, upon 

 superficial strata, has usually been considered as peculiar to the drift 

 period and other still later epochs in our earth's history. The object 

 of this communication is to state a few facts, tending to prove that the 

 causes which produced these appearances have operated in exceedingly 

 remote periods, and at great intervals. 



An instance is mentioned by Professor Emmons, in which polished 

 and ground surfaces occurred between strata of Trenton limestone on 

 Lake Champlain. In these cases, the rock above is stated to be in 

 lithological characters and fossils similar to that below, and that the 

 inferior surface of the upper layer presented an exact cast in relief of 

 the one below. 



I have observed several instances of a similar character in Northern 

 New York, which, from the evidence they furnish of the action of 

 denuding causes in early periods, are worthy of special record. One 

 of the most interesting of these localities is at Deer River Falls, one 

 mile below the village of Copenhagen, Lewis county, N. Y. The river 

 is here precipitated down a chasm in the Trenton limestone, to a depth, 

 it is said, of 270 feet. Near the bottom of these clifls, the sections in 

 the strata present, in several places and at different levels, a peculiar 

 waved line, produced by the removal of portions of the upper surface 

 of a stratum, the lower side of which remains level. The uniformity 

 of stratification is not disturbed either above or below. In several in- 

 stances the rock above has been removed, presenting continuous furrows, 

 three or four inches deep, and a foot broad, with an uniform and par- 

 allel course in this instance, varying but little from west to east. The 

 depth and uniformity of these grooves, with the want of polish upon 

 their surface, would indicate that the rock had not acquired solidity at 

 the time of their formation. Quite a number of waved lines may be 

 seen intervening on the face of the precipice at this place, with inter- 

 vening level strata many feet in thickness, thus indicating a repetition 

 of the causes, with intervening periods of repose. A more interesting 

 and characteristic locality of furrowed surfaces underlaying rocky strata, 

 occurs at Ogdensburg, near the St. Lawrence river, and between strata 

 of calciferous sandstone. The deeper and older grooves extend from 

 north-north-east to south-south-west, while the slighter and more recent 

 ones extend from 10 west of north to 10 east of south. The marks 

 of attrition are quite as distinct as is ever noticed on superficial rock, 

 and were evidently made after the stratum had acquired a solidity 

 quite equal to that which it now possesses. At one locality the fur- 

 rows are seen passing horizontally under an abrupt terrace of the coarse 

 limestone about twenty feet high ; but the exact point of contact was 

 not seen, it being covered by a wall. The surface of the rock above, 

 exhibits here no marks of abrasion ; although, elsewhere, it pre- 

 serves them with great distinctness. After a careful study of the 



