THE SAVOY SCHIST. 157 



Across Blrtiulfovd, wliere the l)e(l.s are much CDvered, and where, while 

 many beds of sericite-schist hitervene in the Chester aniphibohte, the pre- 

 dominant rock is hornblende-schist, the boundary is less clear, and here, on 

 the one hand, hornblendic bands appear in abundance all through the 

 hydromica-schist series, and on the other the intercalated schists mentioned 

 above are identical with the schists of the upper series; l)ut this Ixmndary 

 is of somewhat subordinate importance, and the Chester amphibi)lite already 

 described, althoujih fully deserving separate treatment, both from its im[)or- 

 tance as a horizon and from the geological interest of its various nieml)ers, 

 is quite closely allied to the present series, and the most important bovxndary 

 line lies at the base of the latter. Around the Granville anticline and north 

 of Middlefield, where the amphibolite band naiTows and is interrupted, the 

 boundary is di'awn with less but still with very satisfactory accuracy. 



GENERAL DESCRIPTION OF ROCKS. 



The prevailing rock is a muscovite-schist of medium to coarse grain, 

 with varying but always considerable content of mica, and as this mineral 

 is very generally hydrated the whole series was for a long time called 

 talcose schist, from the soapy feel of the softened mica. The rock is of 

 a light-gray or g-reenish-gray color, and both carbonaceous and feiTU- 

 ginous matter in such form as to darken the rock are very generally 

 absent — a general mark of distinction between this and the subsequent 

 formation. 



Almandine garnet is \gyj generally but very irregularly present, often 

 crowding the sti-ata for great thickness and often wholly wanting. The 

 forms 202 (211); 202 (211), oo (110); and oo (110) appear. The gar- 

 nets frequently reach large size — 25-35°"" — and in several places, especially 

 in Chester, afford fine cabinet specimens. They are often changed to the 

 center into chlorite, and this mineral also often appears in scales, especiallv 

 stretched in long lines along the cleavage faces of the rock, giving the 

 schist a greenist tint, and so far increases at the expense of the mica as to 

 become a chlorite-schist. 



The sericite-schist further carries white, sugary sandstone beds shot 

 through with long, flat crystals of black hornblende, which forms a striking- 

 rock in the cutting nearest the Chester station and appears abundantly 

 farther south in Blandfonl. 'I'his increases at the expense of the other 



