MEMBERS OF THE TACONIC SYSTEM. 61 



extends only a few inches in depth. For this reason, the hest fiekl for studying tlie rocks 

 of this period is the bck here referred to, embracing' the whole country from the Hudson 

 river to the Green mountains. It will be seen hereafter that in Maine we are encumbered 

 with igneous injections, as trap dykes, and perhaps with granitic eruptions ; yet even in 

 Maine the Taconic slate seems to be but little affected as a whole bj^ intruded masses, the 

 most disturbed portions being among the lower members of the Taconic system. 



II. INDIVIDUAL MEMBERS OF THE TACONIC SYSTEM IN \EW-YORK, 

 MASSACHUSETTS AND VERMONT. 



§ 1. LiTHOLOGICAL CHARACTERS AND SUCCESSION. 



The researches and observations hitherto made on the rocks of this system, have not yet 

 elucidated their nature so far as to enable us to determine the best mode of treating them. 

 There is no doubt as to their succession ; but there are some points of inquiry peculiar to 

 the province of geologj', such as whether certain individual masses are to be regarded as 

 subordinate beds or independent rocks, upon which some diversity of opinion may very 

 well exist. On this question, two different views might be adopted and maintained without 

 doing violence to established principles. In the first place, the whole series may be con- 

 sidered as an immense deposite of slate, in which are many subordinate beds of different 

 materials, as limestone, chert or hornstone, breccia, sandstone, etc. ; or, in the second place, 

 those individual masses may be treated as independent rocks, though it will still remain 

 true that some of these masses rest upon, and are succeeded by, a kind of slate whose 

 characters are identical. I shall, however, take the latter view, so far at least as the more 

 important masses are concerned, although there are no very substantial reasons for the 

 adoption of this course. Taking one broad view of the whole system, it may be described 

 as consisting of fine and coarse slates, with subordinate beds of chert, fine and coarse 

 limestone, and grey, brown and white sandstone. These admit, however, of more minute 

 divisions than I have here stated, as will be seen in the sequel. But it is necessary, 

 in the first place, to form some conception of the original position of the masses. Their 

 present position is an inverted one ; that is, those rocks which are really the inferior, and 

 of course the older, are now the superior, and apparently the older ; and we have, there- 

 fore, to reconcile this seeming incongruity. Sedimentary rocks are always deposited in a 

 soft movable state, and usually remain in a horizontal position until consolidated. These 

 rocks, however, are now always inclined, their prevailing inclination or dip being to the 

 southeast, and it is towards this direction that the older rocks are found ; tlie consequence 

 is that the newer rocks, or those towards the west, dip beneath the older, or might even 

 pass beneath them, provided they were prolonged far enough in this direction. To escape 



