OIIIOMTOAT/ ANAI-YStOS AND DiaOUSStON 



491 



giibbro iiml iiiiortliosito gal)l)ro iioL iulcqiuilcly r('|ii'('H<'nl in;;- llic cliiiriuitor 

 of the anorthosito gabbro boni, or olso miglit bo regnrdcd an n diUVrduco 

 whicli Uirow dotil)!- on Lho HiiggcHlcMl ()i'iij,iii of Hie Ivvo I'nckn (■diHioruod. 

 To tbo wi'ilcr tlic; fonnur hcoiiih vawily LIk; more; probahlc. Mince llic aiior- 

 thoHito gabbro UHod is known to bo a Homcwlial, abiiornml idcL, luid llic 

 simihvrities between tbo cNilculnl ion and Ihc anidysis Mccni lo liini also 

 much more signifuiant tban tbo did'oronccH. II. is nol, being argned Ihal 

 tlioy alTord ovidcnc^o oT the truth ol: tb(! a(lva.ne<Ml hypol, bonis, bnl. only 

 that tlioy do not I'lirnisli ground for an argiinuMii againni, il. 



So far as tlio wril,or m aware, no annlyHes of tbo graiiilie ;;iieisHeM of 

 the Adii'ondackH liaNc been made, so lliid. reeoiii'se niiisl. be bad In ('ana- 

 dian anaiyscH in (irdei- In jm'I, iiny (liil;i lur ediiipni'ison willi Hie ;ieid 

 syonitoH. Tlu! only one of tbese known to llm writer in Uiat (|iiii|ed art 

 nundx'r 1(! of tbo lable nf iinalyM(!S and repeaJcd as eoliiinn I of tbo 

 folbivving labl(\ Willi il. are Iwo analyses of grand ie |ihas<'S id' Ihe 

 syenilc, numbers I I and If) (if Hie nriginal table. 



HiO,. . 



Al,()„ 



(3fi() . 

 Naj( ) 



1 



2 



(ID 'Jl 



(IH.Ii 



14.Kf. 



(■I. (ill 



2.(W 



■I.M) 



.)»7 



.2{\ 



'> 1 



>> '> 







4,:t 



.■iJ) 



'i.:i;; 



n.i) 



8 



(IH. IH 

 111.15 

 L'.2(; 

 .111 

 2,'IH 

 '1.22 

 5.51) 



These ar(! siicb l.rillin;.; ditforenceB in composilion Ibat tbere is lil-l.l(! 

 to be gained by nuiking ealeiibilions. Tbo two syeiiilcs diU'er IVnm one 

 another m uwwh as eitlior dilTors iVoni LIk! granite. It is, however, to bo 

 noted tbat the Hyonitos ai'o nearly as siiicooiiH as IIk! granilc-gnoisH, ho 

 that if they liave boon |)ro(lu(;ed from tbo nornial syonite ol." a,bout (I.'J 

 per cent of Hilica by digosl/ion of granite no more aciid than thJH, the 

 amonnl. of granile digeslcd mnsl. (aun'mously exceed IJk^ syenite in Hie 

 nnxtiir<!, wbieli soeniH most improbable. I^jxporittnoo with dllier syenite 

 baibyliUiH of the region has led the wi'itor to tbo viciw that they havo 

 a normal t(!ndenoy to produoe a, 'more a,oid dilTiM'cintiaJ.ion bordcjr. |{ut 

 the detttibid field work necessary to establisb IJiat view is iis yet iiiidolie. 

 If it be tru(!, it followH that the acidity ol' these syenites is duo in wliole 

 or ])art to this nornial dill'erentiation, and only in pai't or not at, all to 

 incorporation ol' malorial From the gi'anite-giKMHS. Such iiioorporalion 

 would, liowover, evidetitly yield a rock quite like the acid syenite, so that 



