DESCRIPTION OF THE GEOLOGICAL MAP. 



This map is a reprint, in the main, of the map which accompanies the first reports. Important 

 additions, however, have been made to it. Parts of Vermont, Massachusetts and Connecticut are now 

 incUided. In addition to these, the range of the Taconic system is colored, and made a distinct part of 

 the map. It occupies a belt extending from the Canada lino to New-Jersey and Tappan bay on the 

 North river, below the Highlands. This system, it will be observed, is divided or split by the primary 

 of the Highlands ; the older part passing on the east side intersects the Hudson at Peekskill, and the 

 superior portion passes on the west side and leads off into New-Jersey, passing through the county of 

 Orange. The primary rocks of IVIassachusetts, Vermont, and Connecticut, which lie in a position 

 nearly parallel to the Taconic system, are colored with lake, and the Taconic system a drab. By this 

 addition, the relative positions of the New- York, Taconic and Primary systems of New-England are 

 indicated. AVe may see the great primary nucleus of New-England as it disappears beneath the oldest 

 sedimentary rock now known, composing the Taconic system ; and the disappearance of the latter 

 beneath the New- York system. The New- York system continues the superior system until we reach 

 Green bay and the sources of the Menomone river, where the Taconic system once more appears, 

 supporting the lower members of the New- York system, and reposing on and supported by the Primary, 

 as in Massachusetts, Connecticut and Vermont. 



The narrow belt of the Taconic system is a remarkable feature in the geology of this country ; it 

 being an immensely thick series, which seems to have been deposited in long and remarkably deep seas 

 that resembled profound clefts in the crust of the earth. 



The different members aie not distinguished by colors : the difficulty of locating them with that de- 

 gree of precision which is required in a map, was considered a sufficient reason for the omission. The 

 oldest or inferior member, the gray sandstone or granular quartz, lies upon the primary in the range of 

 Williamstown and Dalton, Massachusetts, and Arlington, Vermont. The Stockbridge limestone forms 

 a belt immediately west ; and then there is a belt of silvery talcose slate, or magnesian slate ; beyond 

 which the sparrj^ limestone appears in a distinct range, which may be located with some degree of pre- 

 cision, when it is stated that the tunnel of the Great Western Railroad passes through it, which is not far 

 from the line bounding New- York and Massachusetts. The members are regarded as the inferior rocks 

 of the Taconic system. Still west of them there is a wide belt of taconic slates, which contai.ns many 

 subordinate beds of limestone and siliceous slate, and which frequently supports the outliers of the lower 

 members of the New-York system. The Taconic system, as a whole, may be regarded lithologically 

 as an immense slate system, with subordinate beds of sandstone and limestone, both of which are more 

 largely developed upon its eastern border adjacent to the Primary system. 



The New- York system is colored like the former map, which accompanies the volumes already 

 distributed. 



EXPLANATION OF THE AGRICULTURAL MAP. 



The map extends into Massachusetts and Connecticut, The greater part of the area belongs to the 

 Primary system, and is colored lake. The State is divided into six districts, and is numbered accordingly. 

 [Agricultural Report.] 46 



