46 TEANSACTIONS OF THK [NOV. 18, 



limited extent, none exceeding 75 feet in length, and they repre- 

 sent the ahiminous resichie of the dissolved dolomite, mingled 

 with more or less disintegrated limestone and ferruginous matter. 

 They are reddish, white, and blackish, as are also the outcrops 

 of decaying limestone ; — the red color being due to ferric oxide, 

 and the black probably to organic matter. The clays are con- 

 formable in stratification to the limestone, dipping steeply south- 

 east. 



Prof. Martin spoke of the attention that had been attracted 

 by these parti-colored clays, which had been compared in aspect 

 to the Tertiary beds at Gay Head, Martha's Vineyard. He had 

 received a letter regarding them from Prof. T. Sterhy Hunt, 

 and had referred it to Mr. Merrill, whose familiarity with all 

 the neighboring clay-deposits, and with Martha's Vineyard also, 

 rendered him peculiarly qualified to investigate them, as well as 

 the fact that he resided near the points of exposure. 



A vi:jit to the spot made by himself (the speaker), in which he 

 had carefully traversed on foot the line of the railroad from 

 Lower Morrisania to Fordham, proved both interesting and dis- 

 appointing. Traces of the clay exposures were abundant, in 

 material thrown out along the route ; but the sections themselves 

 were apparently concealed almost as soon as developed, by the 

 rapid process of walling-up of the cuttings. At only one point 

 had he gained a clear section that was at all characteristic. 

 [This was shown on the board in a colored drawing.] The spot 

 was a little below 'J'remont Station, on the east side of the road. 

 The colors of the clays are very marked, and larger exposures 

 must have been highly interesting. The varieties found by him 

 [and exhibited in a suite of specimens] were, — white and gray- 

 ish-white, ochre-yellow, bright brick-red, black (very black 

 when moist), and a bluish-green, apparently consisting of de- 

 composed chloritic material. 



