14 



NEW YORK STATE MUSEUM 



be obtained opposite the hotel on the Cascade lakes. The yeliow- 

 green of the diopside, the black of the associated garnet and the 

 white matrix of calcite are in decided contrast. The exposure of 

 limestone is limited and as the surrounding rocks are anorthosite, 

 the diopsides and garnet are probably due to contact metamor- 

 phism. Colored plates 7 and 8 drawn from microscopic slides 

 illustrate the mingling of these minerals. For these and plates ii 

 and 12 the writer is indebted to his friend, F. K. Morris. 



The limestones show the effects of great pressure. The bent and 

 contorted shapes of the included masses of silicates or of the tongues 

 of basic rock apparently representing old dikes and apophyses indi- 

 cate this feature in the strongest manner. Figure i is a sketch care- 



Skc^ch of G.- 



,v,i It L 



L a u e rs 



squcez.eci be.Yive.e.r\. 



> f G n c- . G ^ 



Fig. I Sketch of Grenville limestone squeezed 1)ctween lajcrs of gneiss 



fully made to scale of an exposure on the west bank of the Ausable 

 river, and so near the line with the Lake Placid sheet that it is diffi- 

 cult to decide within which quadrange it falls. The extremely creiiu- 

 lated edge is sufficiently exposed to convince the observer that the 

 limestone was molded like dough. 



In the exposures at and near the pits of the iron mines formerly 

 worked one-fourth to one-half of a mile west of the Ausable river, 

 the Umestones are associated with beds of black, granular pyroxene 

 and with included masses of this and of magnetite in such relations 

 as to indicate contact zones in one small case from the neighboring 

 anorthosite ; in the large instances from the syenite. They can best 

 be described under the heading contact zones. 



The thickest ledge of limestone observed in the fieW is found near 



