( -13.^ ) 



change is not excluded, luive got n (liinly lissile structure, alwaj'S 

 parallel to the axis of the synclinal or anticlinal folds of system 

 and consequently can make widely divei'ging angles' with the 

 oi'iginal line of bedding) ("false bedding"). Tt is to be recommended, 

 in accordance with the original '), now generally current, meaning 

 of the NN'ord, to conline the term /e/' to these rocks, of which roof- 

 slate in the best known representative. Therefore on the ground of 

 the definition given, the above affix, apart from the well-known Rhenish 

 devonian slates, ought to be given to the greater part of the so-called 

 "Fleckschiefer", "Knotenthonschiefer", andalusite-, staurolite-, chiast- 

 olite slates, etc. 



The English term sch/st -) is used for such heterogeneous rocks 

 that the existence of this word bv the side of A^/, slate is fully 

 justified. Not only does schist denote the more or less foliated peri- 

 pherical facies of purely eruptive rocks, which often without any 

 distinct boundary-line pass into adjoining strata of sedimentary rocks, 

 — whether these eru[)tive rocks occur in smaller laccolithes and dykes 

 or in extensive intrusiojis or effusions (as many "trapps"); — also 

 sedimentary rocks can by contact change into schists-, metamor- 

 j)hosing agencies in strongly distui'bed regions can without any 

 distinction on a large scale change sedimentary and eruptive rocks 

 into crystalline rocks, more or less distinctly, sometimes excellently 

 foliated, such as gneiss, eyegabbro, am])hibolite, etc. Though the term 

 schist in its \arious shades of meaning ") and especiall}' the adjective 

 derived from it ^), has got a much wider meaning in Romance languages, 

 yet it finds also there, by the simultaneous use of the equivalents of 

 lei and s/((tc, a more limited application than in German. In connection 

 with this it is pei'haps recommendable, more particularly after English 



1) Jas. Gkuuk, op. cil. 76, 2-20, sq.; Wright, 504; Akch. Geikie, 125— 126 : "In 

 Englanil I he Leim slaie or clay-slate is given to argillaceous, not obviously 

 crystalline rocks possessing this cleavage structure", (syn. aiyillarcoHs sdiist, 

 Fr. phyUitv, phi/llade; schisfe ardoise-, G. Thonachlefer, Tlionylimnuirschiefer). 



~ Planti.in, "schalie, leye oft schevorsteen", uno ai'doise, ardosia, scandula, of. 

 Verwijs and Verdam, IV, 336-837; VII, 224, by tlie side of which stood the mean- 

 ing "rots, leisteen", (cf. also "een leye der scaudaiisieringhe"); old-Saxon, leia, 

 rots, cf. Franck, 558; Ivlugk, 243. Mdl. Dutch had the word in the meaning of 

 "Slate used for roofs", Verwijs and Verdam, l.V, I. c. 



•^) From r;^i>, to split, to sever, to cleave, to divide; adj. verb. 7;>^.jr3;; Arch. 

 Geikie, 124: "a rock possessing this crystalline arrangement into separate folia is 

 in England termed a schist. As Prof. Molengraaff communicated to me, [his 

 term was already used by him. 



■*) Sp. also pizarra cristalina. 



") which coincides with Germ. scJnefrlg, Dan. Norvv. skifrlg, Swed. skiffrig. 



