Plate 17 



Upper tigure. Photomicrograph of the gabbro of plate 16, lower figure. 

 Enlargement 30 diameters, nicols crossed. For description see text, page 92. 



One and six-tenths miles northeast of Pyrites. 



Lower figure. Photomicrograph ; enlargement 30 diameters, plane polar- 

 ized light. Granulation of mixed rock of dioritic composition. The com- 

 minution of the hornblende and feldspar can be readily seen. Outer border 

 of east flexure of sigmoid fold. 



Same locality as shown in plate 12, lower figure; 2.2 miles south of 

 Pierrepont, near roadside. 



