398 SPARRY LIMESTONE. 



formed crystals of calcite. But it is difficult, after all, to describe the general character 

 when other varieties are so common. The white limestone in Colchester differs from that 

 further south, by its fineness of texture and disposition to break up into exceedingly 

 angular fragments. It is harder and less liable to decomposition. We refer to the lime- 

 stone burnt extensively for lime, by Messrs. Penniman and Bates. It differs from the 

 dove-colored limestone of the Hudson River group by superior hardness. But the 

 marble of Shelburne does not differ from that in Middlebury. 



Occasionally the limestone does not appear to have been metamorphosed, but retains 

 its original dark color. This is well marked at Hubbell's quarry, in Bennington. From 

 fifteen to twenty feet of bluish and reddish-white marble are underlaid by seven feet thick- 

 ness of black, thin and even-bedded limestone, with a conchoidal fracture ; having the 

 same general appearance as the most compact limestones of the Trenton group. It is 

 remarkable that such a bed of rocks should occur in the midst of metamorphic rocks, es- 

 pecially as the underlying stratum contains the best formed crystals of calcite we have 

 seen in the whole formation, and that in great abundance. No fossils were found in 

 Bennington after a very cursory search for them, but were seen at two other localities of 

 apparently unaltered limestone, in Danby and Orwell. 



Upon the hill east of Danby corner, there is a considerable thickness of dark gray 

 limestone, with a few grains of sandy particles. It resembles the limestone of the calcif- 

 erous mica schist formation, and is what we should imagine that limestone to have been 

 originally. Its extent is considerable, along the middle range of limestone. A few 

 bowlders from Shaftsbury, full of fossil corals (?), (resembling Stromatojpora) , are 

 obviously from this vicinity. East of Orwell village, is another locality of dark-colored 

 limestone, containing fossils. It is softer than that from the preceding localities, and of 

 a lighter color. 



A similar fossiliferous unaltered limestone is found one mile northwest from Mid- 

 dlebury, and doubtless others may be specified. A dark bluish-colored limestone is 

 often found between the marbles and overlying slates, as at Mt. Eolus, Mt. Anthony, etc. 

 At the latter locality the rock contains masses of hyaline quartz, exceedingly fetid when 

 fractured. At other places, as in Burlington, Brandon and Milton, the limestone is slate- 

 colored and quite soft. This is a variety apt to contain traces of fossils. Sometimes it 

 merges gradually into the softer argillaceous rocks. 



The variety sparry limestone is used by us to denote certain beds of limestone, either 

 white or darker colored, that are completely traversed by veins of calcite or quartz. Prof. 

 Emmons extends the term to embrace all the limestones of the middle range of limestone 

 in Vermont, or that running through Danby, as well as that in Fairhaven, etc., running 

 north until it meets the other limestones. He describes* its structure as follows : " The 

 color of this rock is uniformly gray; it weathers unevenly, by which a rough surface is 

 formed, disclosing in its composition silex and other earthy matter. It contains numerous 

 veins of white calcareous spar which give it a checkered appearance, and masses of quart// 

 which traverse the rock in an irregular manner. It dips to the east at the line of 

 junction with the slate; but after passing further east, the dip is changed to south- 

 west, where it rises into moderate hills whose steepest slope is upon the east side. 



*Geol. Second Dist. N. Y., pages 151, 152. 



