TACONIC SLATE. 95 



cipally for the purpose of preparing the reader to expect a variety of derangements in a 

 Bystem of rocks of a more recent date than the primary schists. I refer to the taconic 

 rocks; for as the latter are surrounded by those ancient igneous formations, it would be 

 very remarkable if they should escape the general derangements which are so common in 

 the former. In fact we find changes in them of the same kind as those of which I gave 

 some account while speaking of the Taconic system in Rhode-Island. 



§ 1. Taconic slate. 



In describing the Taconic rocks of Maine, I shall pursue the descending order, describing 

 first those which appear to me the newest. The slates at Waterville were the first to which 

 I directed my attention. They are of a fine greenish color, nearly as even-bedded and as 

 fissile as roofing slate, and very little liable to decomposition. They are, however, 

 stained brown in some instances, by the decomposition of pyrites which is disseminated in 

 microscopic crystals through much of the rock. Among the crystals, I believe I can re- 

 cognize also the octahedral iron. I consider the presence of these crystals important, 

 inasmuch as they must have been formed by molecular action subsequent to the deposition 

 of the rock. In the magnesian slate, octahedral iron and sulphuret of iron have been 

 formed apparently under the same conditions, but in much larger specimens. In the taconic 

 slate at Waterville we find the fossils upon the same layers, showing very satisfactorily 

 that the presence of metallic crystals is no objection to the view I have taken of these slates, 

 particularly as it regards their sedimentary character. Interlaminated with the fine green- 

 ish slate are calcareous bands, though by no means rich in calcareous matter. They are 

 thin-bedded, and scarcely differ from the beds described in New-York. I may go still 

 farther, and say that we find here the same series of beds in the taconic slate as in New- 

 York. I noticed in particular the coarse brecciated beds, similar to those formerly called 

 greywacke ; consisting, however, of a diversity of materials, as angular grains of quartz 

 stained with chloritic matter, and disseminated carbonate of lime, which often disintegrates 

 and falls out, leaving rather a rough spongy mass of silex or quartz stained with oxide of 

 iron ; and what I considered as quite remarkable, was the existence of hemitropic crystals 

 of albite in the same coarse beds, under the same condition as in New-York. These beds 

 are traversed by thin seams of quartz, which give the mass a chequered appearance, look- 

 ing at a distance like the sparry limerock. All the subordinate masses run parallel with 

 the beds of the slate : when one is contorted, the other partakes of the same sinuosities. 



The points that I first examined at Waterville, are not far from the centre of the range, 

 the most important of which is that upon the banks of the Kennebeck near the village, 

 where the Nereites are found. The slates are nearly vertical, with only a slight dip to the 

 east: their trend is N. 10° E., varying, however, from this direction to northeast and 

 southwest. At West-Waterville, five and a half miles west from Waterville proper, the 

 same thin beds of slate appear, interlaminated also with silico-calcareous layers. The 



