FOLDS. 



409 



connections of the limestones with the middle range of quartz rock, etc. Consequently it is extremely 

 difficult to become satisfied respecting the true relations of the Eolian limestones to the adjacent rocks. 



Two faults are evident in the limestone : one north of Danby Mountain, showing that the whole ot 

 Danby Mountain and Mt. Eolus have been raised up bodily, and in West Kutland. The latter case is 

 made evident by the sudden change of the marble from one side of the valley to the other, and is probably 

 connected with the gap in the Taconic range of mountains, to the west. 



The schists upon the top of Danby Mountain must have been once connected with those in Danby, north 

 of the fault ; and probably the limestone is newer than the quartz rock. Hence there must be another 

 fault between the Eolian limestone and the quartz rock. From the relations of the limestone to both the 

 quartz rock and schists, one would think the latter were identical, in examining the region about Mt. Eolus. 



Several local sections and variations in dip demand notice. First we present a section (Fig. 260), drawn 

 by Professor Adams, to represent the undulations of this limestone in Middlebury. The ledge repre- 

 sented is thirty feet long, a, a, a, represent concretionary masses of limestone. 



Fio. 260. 



FIG. 261. 



Fio. 262. 



Plicated Limestone in Middlebury. 



Fig. 261 represents two minor folds in a general fold at White & Higgins' marble quarry at Whiting 

 Station, in Leicester. The width of the whole fold is forty rods, and it may be traced a considerable dis- 

 tance north and south, as it constitutes a hill. In the figure, a, a, represent blue 

 marble ; the interior of the folds, surrounded by sparry seams, b, b, of thick-bedded 

 strata. The remainder are mostly marble, of various colors, striped or variegated, 

 whereby the same layer may be readily traced upon both sides of the anticlinal. The 

 small folds are three feet across. 



This figure suggests an important topic to be well considered in the geology of the 

 whole State : the limestone dips in the same direction upon both sides of the fold. 

 We know of the existence of the fold only because 

 the top of it hag not been worn away. Suppose, now, 

 that the fold should be worn down to the line c, c, 

 what evidence should we have had of its existence ? 

 Merely the correspondence of the layers upon the different sides of the axis. 

 And in metamorphic rocks, where essentially the same kind of minerals are 

 found in almost every layer, it would be very difficult, without the most tedi- 

 ously thorough examination, to discover these inverted anticlinals. We 

 suspect the presence of several of these anticlinals in this limestone formation 

 where there is little evidence of them ; particularly between the limestones of 

 Brandon and Sudbury, upon Section VII. If this is so, then there may 

 have been a fold between the whole western spur and the principal range, 

 inclosing most of the slates and schists. And in such cases the rocks may be somewhat different upon the 

 different sides of the anticlinal in consequence of different degrees of metamorphism. 



This principle would be a useful one to employ, where it is possible, in the solution of the problem of the 

 thickness of the other metamorphic rocks. 

 27 



b a b aba 

 Inverted Anticlinal. 



W. 



Fold near Clarendon Springs. 



