100 FOX ISLANDS. 



which, however, occasionally appears, as at Camden, above all the other rocks, and then 

 sinks deeply and disappears beneath them. This state of things causes a great deal of per- 

 plexity, confusion and disagreement among observers ; and it will require the utmost care 

 and attention on the part of all, to reconcile the discrepancies and differences of opinion 

 on this question. On many of these subjects, much is yet to be learnt in this country ; 

 and though we are here pushing our researches among the newer rocks with great zeal, 

 nnich remains to be done among the older, and to be learnt in relation to the origin of 

 rocks and parent beds. • 



§ 2. Fox ISLANDS. 



The islands called Fox islands, lie off from Camden twelve miles. They form low 

 ridges, or high reefs or outliers from the main land, and are particularly well located as 

 fishing stations. 



The formation of these islands is very similar to that of the main land. The principal 

 difference consists in the greater proportion of metamorphism exhibited in the islands. The 

 slates are particularly altered. The cause appears upon the spot ; few places furnishing 

 such a number of dykes as are found on some portions of the coast. The effect exhibits 

 itself in a hardening of the strata and a crowding together of the masses, and in the de- 

 velopment of many hard oval nodules, and in many instances imperfect crystals of felspar. 



Those slates which are unchanged are thin beneath and usually dark colored, and very 

 often charged with sidphur, which imparts to them that peculiar character that has given 

 them the name of plumbaginous slate. When only a slight change has taken place, there 

 is simply a glossy surface, a sort of resinous lustre. 



The dykes are the ordinary greenstone, though coarse, yet nothing peculiar ; but they 

 contain many nodules of smooth quartz much like water pebbles, solid throughout, or with 

 merely a slight cavity in the centre. These break open readily, and some become loose by 

 atmospheric action. The islands, however, are composed of the magnesian slate and trap 

 dykes, twenty five or thirty feet wide, to which must be attributed the strange metamor- 

 phosis the rocks have suffered Ijoth in texture and mechanical arrangement. 



We are unable, in consequence of the concealment of the rocks in this direction, to 

 estimate the width of the Taconic system : (hey dip N. 55° W. The system ranges up 

 the Penobscot into the interior of Maine ; but in consequence of the proximity of igneous 

 rocks, and the changes which they have undergone, as well as their resemblance when 

 thus changed to the primary schists, it may still be difficult to mark out the distinct belt of 

 country over which it prevails. 



Having completed my examinations at Camden, I proceeded to Thomaston, where for 

 a long time beds of limestone have been wrought for marble, but more extensively used 

 and burnt for quicklime. I had the same intention as when visiting the Rhode-Island 

 quarries of limestone, namely, the determination of the age and relations of the rock. 

 Thomaston is about seven miles southeast of Camden, and lies in the direction of the range 



