THICKNESS. 



417 



Milton Falls, limestone and slate are both found. At the summit level there is slate ; 

 near a railroad crossing the limestone is nearly horizontal; north of this as far as the Falls, 

 every ledge is limestone, and that generally of a soft slate-colored variety, like the fossilif- 

 erous limestone further south. Beds of limestone are in the quartz rock at Milton Falls, 

 and the formation terminates in a point near the north line of Milton. 



The thickness of the Eolian limestone is nearly 2000 feet. The best place to determine 

 it is in the east part of Dorset, upon Mt. Eolus. The strata of limestone are nearly hori- 

 zontal, composing the greater part of the mountain, and are capped by talcose schist. 

 The base is not reached, but it is certain that the measurement does not embrace any part 

 of the rock the second time. Fig. 264 gives a section of this mountain. The barometer 

 showed 1970 feet difference of elevation between East Dorset and the top of the limestone. 

 There is no doubt that many feet of thickness of layers out of sight at the mountain should 

 be added to make the whole thickness sufficiently great. We have not carefully compared 

 this thickness in Dorset with what might be deduced from other sections, but express the 

 opinion that the limestone is rather greater in amount here than elsewhere. Hence the 



Fio 264. 



W. 



Section through Mt. Eolus. 



appropriateness of applying the name, Eolian limestone, to this formation, especially in 

 preference to the term Stockbridge, for only a part of the formation is developed in that 

 town, and that in an inferior condition to this. The thickness of the same range in New 

 Jersey, as given by Prof. H. D. Rogers, agrees essentially with this, and generally in 

 Vermont the thickness would not fall short of this 500 feet. But it does seem rather 

 strange that there should be such an immense pile of nearly pure carbonate of lime in 

 the same mountain mass. 



The numbers in the following enumeration of the thickness of the different beds of 

 limestone upon Mt. Eolus, refer to the specimens collected from them upon the mountain 

 and deposited in the State Cabinet. The specimens illustrate Fig. 264. In ascending 

 from East Dorset to the cap of schist, we pass the following beds : 



Schistose limestone, with slaty seams, 106 feet ; 

 Blue limestone, 47 feet ; No. T |^. 

 Silicious limestone, 25 feet ; No. T $ ff . 

 Bluish gray limestone, 110 feet ; No. T | ff . 

 Limestone with ferruginous seams, 23 feet. 



to T | T . 



