^ 



Trans. N. V. Ac. Scz. 182 j2(„e 5, 



wide, rising in Westchester County, and discharging its waters into 

 Long Island Sound, nearly opposite College Point. 



It occupies, however, the bottom of a valley, which; at Williamsbridge, 

 must be at least half a mile wide, probably more, and two hundred 

 feet deep below the summits of the hills which bound it to the east and 

 west. This great depression extends northwardly with the river, but 

 I have not studied it any further north than White Plains, where it is 

 quite broad. At a point about three-fourths of a mile below the 

 Williamsbridge station of the Harlem Railroad, this valley is some- 

 what narrowed, and much interrupted by a ridge of rock running 

 parallel with the present course of the stream, viz., very nearly north 

 and south. The Bronx flows through a narrow gorge cut out of this 

 rock. It is near the northern end of this ridge where the pot-holes 

 under consideration are situated. Leaving the train at Williamsbridge, 

 and ascending the stream, we pass through a stretch of swampy 

 ground of considerable botanical interest, it being the only known 

 habitat about New York for Artsoema Dracontium, the " green 

 dragon," we pass the old bridge before mentioned, and enter the grove 

 of hemlock. The first pot-hole to be observed is quite imperfect, only 

 a portion of the western side now remaining, the rest having been 

 broken away. It bears S. 50° W. from the western end of the bridge, 

 at a distance of 76 feet. The bottom of the pot is about 18 feet 

 above the present level of the Bronx at this point, but this is less than the 

 natural height would be, as the water is backed up by a dam half a mile 

 below. Measurements indicate that the total depth of the hole must 

 have been about nine feet, and at half its height the diameter not less 

 than ten feet. This must, however, have very rapidly decreased 

 towards the bottom. 



Proceeding 136 feet south from the bridge, and then up the rocks to 

 a point 63 feet from the river bank, the second pot will be found. This 

 is much more perfect, and is quite a noticeable object. The bottom of 

 this one is twenty or twenty-two feet above the present water level. 

 The hole is oval in section, about four-fifths of the original outline still 

 remaining, only the outer (the eastern) end being broken away. Its 

 dimensions are as follows : 

 Total indicated depth, 10 feet. 

 Depth of nearly perfect lower part, 4' 6". 

 Depth of entire basin at the bottom, 10". 

 Shortest diameter, 5'. 



Original longer diameter probably about 6'. 

 Distance from back to broken face, 4' 7". 



The lovver part of this pot is very well preserved ; the bottom and 

 sides are very highly smoothed, indeed quite polished. The upper por- 



