274 BOARD OF AGRICULTURE. 



results agree within 600 feet, which is a small error considering the 

 roughness of the estimate. 



Last year we spoke of the great interest attached to this nearly 

 isolated basin of mica schist, on pages 160, 161. This interest is 

 increased by running a section across it, and ascertaining its syn- 

 clinal form. Our observations of this year will enable us to give 

 its limits with more precision on the second maps, and we need not 

 here give all the details of its limits and position. The basin is 

 probably of Cambi'ian age, judging from lithological characters 

 alone. 



Porphyrilic Granite. 



The next formation is porphyritic granite, which is very exten- 

 sive, being e of the section. There is very little to say about it. 

 Every ledge showed a distinct porphyritic character, and it is won- 

 derful that such an immense amount of this variety of granite 

 could exist. The band is eleven miles wide here, and extends to 

 an unknown distance northeasterly and southwesterly. This re- 

 gion is very mountainous, many of the peaks being fully as high 

 as those in Eden. The mountains are scattered peaks, not one 

 continuous range, although the whole granitic mass may be con- 

 sidered as belonging to one general range. Another feature of 

 this region is the presence of an immense number of huge boulders 

 of porphyritic granite. This is a characteristic of almost every 

 granite formation in the State. The boulders being mostly of the 

 same material as the underlying rock, cannot have been transported 

 a great distance. The soil over most of this belt is rather inferior. 

 The route of the section is along the Telegraph road from Ells- 

 worth to Bangor, passing through the Falls village. North Ellsworth 

 and Dedham, east of Fitz's pond. Between Orland and Ellsworth 

 this granite belt is twelve miles wide, and is not all porphyritic. 

 The dissemination of large crystals of potash feldspar (orthoclase) 

 through this rock, makes it a beautiful variety to look upon, and 

 we noticed many places by the way where good quarries might be 

 located. 



Quartz Rock. 



Very near the boundary line between Dedham and Ilolden, 



the granite disappears and quartz rock succeeds, dipping 70° S. 



70° E., as it were, beneath the granite. Some planes of a jointed 



structure dipped 70° S. 20° W, in this vicinity. This rock merges 



