RECORDS. 669 



The regular paper of the evening was then deHvered by Pro- 

 fessor Stevenson. The Schoharie valley is an indentation in the 

 Helderberg mountains, about 35 miles southwest from Albany, 

 New York. It shows a section from the Hudson to the Ham- 

 ilton groups with almost continuous exposures at various locali- 

 ties. This was examined during the summer of 1899 with the 

 view of making comparisons with conditions observed in parts of 

 the Appalachian region, within Pennsylvania and Virginia. 



There are some notable contrasts between the northern and 

 the southern sections. At Schoharie, the Medina is wantine 

 and the greenish shales of Clinton rest on the Hudson. In 

 southern Pennsylvania and in Virginia the red and white Medina 

 are both present and Hudson forms pass upward into the red 

 Medina, occurring abundantly in southwest Virginia in a bed 

 100 feet below the white Medina. At Schoharie, the Niagara is 

 differentiated physically from the overlying Waterlime, but much 

 of the Niagara fauna passes into the Waterlime ; in localities 

 further west and south, the Salina shales intervene and there is 

 no passage of fauna. The upper Waterlime at Schoharie differs 

 greatly in color and composition from the Tentaculite or lower 

 division of the Helderberg, but at least two forms, most charac- 

 teristic of the Tentaculite, are found in the upper waterlime. 

 These forms were not observed by the writer in the Waterlime of 

 southern Pennsylvania. The several subdivisions of the Helder- 

 berg are very distinct physically, the boundaries of each being 

 sharply defined ; but the physical changes were such as to cause 

 only gradual disappearance of the several faunas and forms, 

 which persist throughout, showing little variation. The passage 

 from Helderberg to Oriskany at Schoharie is abrupt to the last 

 degree — from a very good limestone to a ferruginous and only 

 slightly calcareous sandstone. The faunal change is as abrupt 

 as the physical. Here again the contrast is very great, for in 

 southern Pennsylvania the passage from Helderberg to Oriskany 

 is very gradual, through a silicious limestone containing forms 

 belonging to each. In southwest Virginia, the upper part of the 

 Helderberg becomes silicious and in some localities is almost a 

 sandstone. 



