No. 112. j 789 



black marble. At Port Henry, is exhibited a remarkable and 

 scarcely defined and promiscuous mingliog of various strata of 

 rocks and minerals. Serpentine, mica in large and beautiful mas- 

 ses, gneissoid granite, primitive limestone, are conspicuous. The 

 pure white of the calcareous limestone, spotted by the sparkling 

 black specks of plumbago, form most beautiful cabinet specimens. 

 In Keene, 1 found specimens more rare and exquisitely beautiful 

 of this limestone, dotted by bright green crystals of sahlite. 

 Verd antique occurs in large veins at Port Henry, and is an ex- 

 ceeding rich and brilliant material. An observant gentleman of 

 that place affirmed that a fossiliferous limestone rock, presenting 

 a perfect stratification, might be seen at low water on the mai'gin 

 of the lake, forming a substratum to these primitive rocks. 



The granular limestone which^ crops out at Port Henry, ap- 

 pears in Ticonderoga, near Lake George, and prevails extensively 

 in Schroon and Minerva. I found but one manifestation of the 

 rock in North Elba, upon the farm of Mr. Hinckley, where it 

 develcpesin a ledge, upon a side hill. It appears usually com- 

 bined with sulphates, phosphates, or other foreign substances. 

 The hypcrslme rock projects from themountainsiu Westport, and, 

 incidentally traversed by limestone, predominates. The primitive 

 rocks prevail in the s(!ruthern section of the town of Essex. Here 

 occurs that very extraordinary exhibition of porphyry so elabo- 

 rately discussed in the report of Professor Emmons. This rook, 

 extending over the surface upon several acres, is peculiarly beau- 

 tiful in its color, structure, a:xl singular dentritic formation. It 

 affords perfect demonstration of an igneous agency, most potent 

 and terrific, that rent asunder the earth, fused and ejected tliis 

 vast rock. The extreme hardness of the porphyry, is a marked 

 characteri::tic. Struck with the steel hammer, it evolves a bril- 

 liant Ci.rruscation of lii^^iit and sparks. My attention was di- 

 rected to another remarkable exhibition of porphyry, upon the 

 premises of Mr. Clark, on Willsboro' point. This vein, about a 

 foot wide, is interjected in a seam of blue limestone, and the rock 

 has been evidently dismembtTcd in the process. Scarcely a frag- 

 ment of tlie disrupted limestone remains, near the porphyry 

 vein, but by a singular coincidence, or as an evidence of the 

 amazing power of this agency, I was informed that fragments of 



