1904., ABBOTT — ARTIFACTS BENEATH DEPOSIT OF CLAY. 161 



ON THE OCCURRENCE OF ARTIFACTS BENEATH A 

 DEPOSIT OF CLAY. 



BY DR. CHARLES CONRAD ABBOTT. 



{Read AjJril S, I904.) 



A recent examination of the surface soils of a shallow valley-like 

 depression in upland fields, elevated 50-70 feet above the Delaware 

 River and its flood-plain, made evident that the present little brook 

 was not the original and only watershed of this tract of land, but 

 the remnant of a stream of greater volume which had at one time 

 practically filled the valley. To reach the flood-plain of the present 

 river, the brook of to-day passes through a deep valley that has 

 been worn into the face of the bluff that extends for a long distance 

 parallel to the river's course. A bird's-eye view of the region 

 shows at a glance that when the present flood-plain was permanently 

 under water, the gully did not exist in its present width and depth 

 and the greater volume of the present brook emptied directly into 

 the river. As the river's volume decreased and the stream con- 

 fined itself to the channel now existing, the brook wore away the 

 face of the bluff until it reached the abandoned river bed or what is 

 now a wide meadow, ordinarily dry and cultivable, but occasion- 

 ally overflowed to a considerable depth. 



In a cross-section of the upland valley, extending over two 

 hundred feet in width., it was found that immediately below the 

 present soil and deeper sand as yet unaffected by decomposition 

 of vegetable matter, there was a well-defined deposit of clean, sharp 

 river sand, a few pebbles and a trace of clay that resulted in a slight 

 cementation of the mass. Besides this condition, there was at one 

 part of the section, some forty feet in extent, a deposit of clay, 

 comparatively free from grit and so compact that no object could 

 have intruded. It was nine inches in thickness and twenty-four 

 inches from the surface of the ground to its base, which was com- 

 pact coarse sand, pebbles and a little clay. Resting on this base, 

 an unquestionable bed of a water-course, were artifacts, consisting 

 of flakes of argillite, artificially produced and the hammer-stones, or 

 oval pebbles, with the ends battered by continued violent contact 

 with other minerals. 



A closer examination of the spot indicated clearly that the clay 



PROC. AMER. PHILOS. SOC. XLIII. 176. K. PRINTED JULY 13, 1904. 



