EXPLANATION OF PLATE 13. 



Figure i. — Fourchite from the main sill, showing granulitic character of the 

 augite. The prisms of zoisite, and the filmy areas of blue 

 amphibole, cannot be delineated, apart from the general ground 

 mass, in a drawing of this degree of magnification. The dark 

 patch is an aggregate of pyrite. x 40. 



Figure 2.— Spheroidal facies of fourchite (spheroidal basalt) at Point Blunt, 

 with skeleton crystals of plagioclase. The longer, lighter 

 colored brushes are composed of plagioclase microlites, while 

 the shorter and darker bunches are probably augite. The 

 greater part of the slide is occupied by a gray cloudy glass. 

 One porphyritic crystal of plagioclase is shown that has been 

 broken in the magma, and also contains an embayment filled 

 with the glassy base. - 40. 



Figure 3.— Altered radiolarian chert from near the contact with the serpen- 

 tine dyke, showing the characteristic mode of development of 

 the glaucophane in long, hair-like crystals, during an incipient 

 stage of the metamorphism. Although this particular slide is 

 from the serpentine contact zone, it might just as well represent 

 identical facies found alongside the fourchite. It is impossible 

 in a drawing to give any adequate idea of the beauty and deli- 

 cacy of these sheaves of blue capillary crystals lying in a mat- 

 rix of clear quartz grains that are dusted with minute garnets 

 and other crystal grains. < 40. 



Figure 4. — Section of the typical glaucophane schist, from the contact zone 

 west of the serpentine dyke, cut at right angles to the direc- 

 tion of schistosity. The cross sections of the amphibole show 

 the frequent zonal structure, while the occasional longitudinal 

 sections exhibit the transverse parting and displacement referred 

 to in the text, x 40. 



