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GEOLOGY. — The calcite marble and dolomite of eastern Vermont. 

 T. Nelson Dale. U. S. Geological Survey Bulletin No. 589. 

 Pp. 67, with maps and sections. 



Some of the rocks discussed are of pre-Cambrian age and associated 

 with granite-gneiss. Some are of Cambro-Ordovician age and appear 

 to be sporadic in a great schist mass. A few are probably of Ordovician 

 age and are parts of narrow impure calcareous belts. Twenty varieties 

 of marble and dolomite are described. 



Of special interest is the occurrence of finely interbedded coarse 

 l)ink calcite marble, colored by manganese, with a white fine-grained 

 twinned dolomite. Attention is called to some recent French deter- 

 minations of the presence of manganese both in the calcareous and 

 soft parts of marine moUusks, and hence to the probability that the 

 pink marljles are of organic origin and to the possibility that the inter- 

 bedded dolomite was formed by chemical precipitation. 



The presence of actinolite and diopside schist along the contact of 

 marble and granite-gneiss, and of felty asbestos along the joint and 

 bedding planes of marble and dolomite are regarded as reaction 

 products under regional metamorphism. 



A marble synclinal outlier is described, illustrating in miniature 

 principles governing mountain masses in a region of folding. This 

 has been transversely folded in the direction of the pitch, while the 

 underlying schist has acquired slip-cleavage with a strike parallel to 

 the pitch. 



Attention is called to the frequent occurrence in the Cambro-Ordo- 

 vician schist of Vermont of the interesting secondary twinned albites 

 first described by Wolff and Whittle. These enclose plicated beds 



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