W. B. Dwight — Recent Explorations, etc. 27 



the admission of steam, constitute the entire apparatus. Seated 

 in the box late that evening, in utter darkness, while the attend- 

 ant had gone outside with the lantern to get a pail of cold 

 water, I heard, in the stillness, sounds deep down in the steam 

 crack, rumbling and hard noises totally unlike the soft hissing 

 or sputtering of the steam. Fearing that my imagination lent 

 strength if not being to these sounds, I went to a crack outside 

 and, at the risk of pitching in head-first, listened carefully. The 

 same noise was heard distinctly, not unlike that of an earth- 

 quake, but feebler. 



Art. III. — Recent Explorations in the Wappinger Valley Lime- 

 stone of Dutchess County, N. Y; by W. B. Dwight. 



No. 6. — Discovery of additional fossiliferous Potsdam Strata, 

 and Pre-Potsdam Strata of the Olenellus group, near Pough- 

 keepsie, JV. Y. 



The last one of the preceding papers of this series* 

 announced the discovery of fossiliferous strata in arenaceous 

 limestone of the Potsdam group on the Smiley farm, in the 

 very outskirts of the city of Poughkeepsie ; and also the ex- 

 tension of these strata along a line of faulting with the slates 

 of the Hudson River group, to a point on the river three miles 

 south of the city. It was also stated that these strata form the 

 western margin of a belt of limestone from 3000 to 6000 feet 

 in width, which is here the most western of three parallel and 

 contiguous limestone belts, separated by Hudson River shale ; 

 and that there was no evidence in my possession to show how 

 much of this breadth was occupied by the Potsdam, and how 

 much possibly by Calciferous and Trenton rocks, except the 

 presence of a single narrow ledge of fossiliferous Trenton on 

 Kimlin's farm very near the eastern edge of this belt. 



Further researches, during the spring of 1886, resulted in 

 making known the presence of a proportionally large extent of 

 Potsdam strata in this particular limestone belt, and in other 

 localities in the more northern part of the county. A ledge of 

 Potsdam containing Lingulepis pinniformis was found about a 

 hundred feet east of the public road on the farm of R. J. Kim- 

 lin, and a little north of his barn. This ledge lies only a short 

 distance northwest of the Trenton ledge on Kimlin's farm, 

 previously mentioned, and whose exact position is indicated on 

 the stratigraphic map of this locality published with my pre- 

 ceding paper. The indications would point to a possible fault 

 here between the Potsdam and Trenton. 



*This Journal, February, 1886. 



