MEMBERS OF THE TACONIC SYSTEM. 
61 
extends only a few inches in depth. For this reason, the best field for studying the rocks 
of this period is the belt 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 by intruded masses, the 
most disturbed portions being among the lower members of the Taconic system. 
II. INDIVIDUAL MEMBERS OF THE TACONIC SYSTEM IN NEW-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 geology, 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; the 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 
