324 E, Billings on some of the 



" On the Taconic Bocks ; by Prof. C. B. Adams. — The nortli 

 part of Addison county, Vermont, possesses peculiar advan- 

 tages for the study of the so-called Taconic rocks, since here they 

 pass from a highly metamorpliic to a slightly raetamorphic con- 

 dition and have been much less disturbed. Some of the typical 

 Taconic rocks disappear, or more probably pass gradually into 

 rocks of the Lower Silurian system. 



" One of the most conspicuous of the rocks of this region, is a 

 red sandrock, which Dr. Emmons regards as at or near the base 

 of the New York system, but which overlies the Champlain 

 r>ivision, in the order of red sandrock, Hudson river shales, Utica 

 slate, Trenton limestone, and La Motte limestone. 



" A section was exhibited of Snake mountain, in which these 

 rocks appear by an uplift with their relative position unaltered. 

 The two lower formations are identified by their appropriate fos- 

 sils, which occur abundantly ; the Utica slate by its position and 

 lithological characters; the Hudson river shales by the same 

 characters, and by their upper member, which is an argillaceous 

 limestone co"ntaining the stinted forms of Choetetes lycoperdon 

 which are usual in this the last period of the existence of the 

 species. The red sandrock lies upon the last named rock in ac- 

 tual contact, with a moderate easterly dip. The upper part of 

 this section is repeated in the line of the strike in several other 

 locahties, but one only, Buck mountain, three miles north, has 

 sufficient elevation and steepness to exhibit the lower part of the 

 series. 



"The assertion which had been made, that there is a line of 

 fracture high up the side of the mountain, above the Trenton 

 limestone, was shown to be entirely unsupported by any facts. 

 Not only is there no evidence that such a line of fracture has 

 brought up the shales from beneath the Trenton limestone, but the 

 fossils in the upper member of the shales prove that the present 

 is their original relative position. But these shales are the 

 Taconic slates of the Taconic system. 



" From position, therefore, it is inferred that the red sandrock if 

 more recent than any of the Champlain Division. Its fossils af- 

 ford less demonstrative evidence. With the exception of Fucoids 

 they are rare, having been been found only at Highgate, where 

 fragments of the shields of trilobites, having some resemblance 

 of Conocephalus, occur very abundantly, and atrypahemispherica (?) 

 very rarely. These fossils, especially the latter, if correctly 



