108 MINERAL PRODUCTS OF THE TACONIC SYSTEM. 



Anollier position will also appear from this discussion ; or if it does not appear, it is not 

 the loss true ; namely, that the system in cjiiestion has been studied by piecemeal, and the 

 whole plan of it worked out of a continually increasing stock of facts from year to year; 

 so that it has been built up from one staging to another, as materials were found to fit 

 together. Now in this mode of building, we are very liable to place some of our materials 

 with the wrong side uppermost, even if we do not arrange them wrong altogether. Hence 

 one part of our business has been occasionally to pull down some of the superstructure, in 

 order to readjust the pieces of which it was composed, and to discard or appropriate as was 

 found conducive to its symmetry, and very likely further emendations will still be required. 



Beds suitable for flagging occur in the Taconic slate, and in the thin beds associated with 

 granular quartz. The former are highly calcareous : they are quarried in rhombic slabs, 

 formed by the natural joints of the rock ; they are very strong, exceeding the sandstones 

 in fuamess ; and they are far superior to the limestones, as they usually come out without 

 trimming. The quartz rock is also useful for flags, but its surfaces arc harsher and rougher. 



The attention of the public has not been sufficiently directed to the importance of the 

 construction of good walks through the streets of our villages ; and thus the stone not 

 being called for, the quarries have rarely been opened. 



A variety of the slate flagging has been discovered in Washington county. It is in a 

 compact mass in slate, without joints, and is almost as diflicult to break in one direction as 

 another. When raised and sawed, it has the appearance of soapstone. 



CONCLUSION. ' 



The independence of the Taconic system is sustained or proved by the following facts : 



1. Position. It rests unconformably upon primary schists, and passes beneath the New- 



York system, the oldest and inferior members of the latter being superimposed 

 unconformably upon the Taconic slate. 



2. Dissimilarity of organic remains. Thv. .JVereites and other fossils of the Taconic slate 



are unknown in any of the members of the Champlain group. In addition to 

 which, it is important to bear in mind the fact, that in this group the mollusca of 

 the New-York system are also wanting. 



3. The members of the Taconic system have a different arrangement. The sandstones, lime- 



stones and slates are not only different in their relative position, but they are much 

 thicker than those with which they have been supposed to be identical in the New- 

 York system. ' 



I leave it for future observers to determine whether the preceding positions have been 

 sustained in this treatise or not ; and inasmuch as it is now important that our palaeozoic 

 base should be determined by observation, it is to be hoped that the subject, with this 

 special view, may receive the attention it deserves. 



