PETROGRAPHY. 341 



(/)) CONTACT MKTAMOUIMIISM. 



Gkeim, G. Dii; Diabas-Coutiictinetaiiioipho.se zii Wcilburg a. d. Lahii, pp. l-IJl. Ono 

 plate. Neues Jabrb., 168a, I. liaud, Ist Heft. 



IIaukkr, Alfkkd. Woodwanliaii Museum. Xott's ou sonic Augk'sey Dykes. (Jeol. 

 Maj?., Septeuilier, 1887, ]». 401). 



DescriliCH the roeks as Augite-audesites, .and Doleiites. A <like of the latter 

 rofdc at Plas-Newydd is described as haviuj;' at <!outact converted a bed of cal- 

 careous shale into "a kind of lydiauite, containiui; calcite and clusters of j^jirnet 

 and analcinie crytals." 



Richards, Oaky F. Lithological notn on Contact I'henoineiia in South Carolina. 

 Hull. Uenison University, Parts i aiul ii, vol. i\', 1888, pp. .")-!(). 



Stecheij, Ekn.st. C!ontacter.sclieinungeu an schottischen < >li viiidiabasen. Min. 

 u. pet. Mittheilnnj^cn, ix, Hand, ii n. Ill Heft, pp. 14.")-'i(l.'>. One i)late showing 

 niicrostructure. 



Williams, GkoKcJK H. The contact inetamorphisin produced in the adjoining Mica- 

 Hchists and Limestones by the Massive Rocks of the " Cortlandt Series" near 

 Peekskill, New York, Am. Jour. Sci., October, 1888, vol. xxxvi, pp. 259-209. 

 Oue plate showing micro-structures. 



(c) UEOIOXAL MiyrAiMORPIIXSM." 



Barrois, C. Modilications ct Transformations des Gr.-inulites du Morbihan, Lille, 

 1887. Auuales Soc. G6ol. du Nord, xv, 1887. 



BoNNEY, T. G. Notes on the structures and relations of sonui of the older rocks of 

 Brittany. Quar. Jour. Geol. Soc, August, 1887, vol. XLiii, No. 171, p. 'Ml. 



l^iscusses the structures of the crystalline shists and their probabh; origin ; 

 their age, to what extent crystalline and sedimentary rocks are affecteil by intru- 

 sive masses and the re.semblance of such secondary structures to gneisses and 

 schists commonly regardcul as of Arcluean age. The rocks carry, besides glauco- 

 phane, .abundant garnets, ejiidote, green hornblende, white mica, quartz, sphene, 

 rutile, and hematite. They are commonly schistose in structure and occasionally 

 banded, the banding being produced by a predouiiuauce of epidoto or sometimes 

 glaucophane. The rocks are sometimes extraordinarily rich in glaucophane, 

 though the individual crystals are not generally large. The writer agrees with 

 Dr. Barrois, that the crystallization of the mineral has taken place since the folia- 

 tion of the rocks, as they show no signs of strain or fracture. The garnets, on the 

 other hand, existed prior to the foliation, as witnessed by their shattered conditinn. 

 The rock appears iuterstratilied with the adjacent schists; l)ut, neverthehiss, Pro- 

 fessor Bonuey is inclined to regard it as an erui)tive, altered by pressure. He has 

 further described the gneisstis of the district around (^uimijerld with especial ref- 

 erence to theJr original and secondary structures, and the gneisst«, granites, and 

 amphibolites of the Roscoff and Morlaix district. Mis conclusions sini that while 

 lioth igneous and stratihed rocks ha\e undergone a certain amount of pressure 

 metamorphism, the igneous rocks b(!ing converted into gneisses and schists, yet 

 many of the Brittany gneisses and schists wisre <!vidently true foliated rocks 

 anterior to the earth movements. Contact metamorphism produced by igneous 

 rocks on the Paleozoic sediments docs not jiroduce rocks which resemble tlie pre- 

 sumable Archa-an gnei.sses and schists. 



On some results of Pressure .and of the Intrusion of Granite in Stratified Paheo- 



zoic Rocks near Morlaix, in Brittany. Quar. .Jour. Geol. Soc, No. 17:5, February, 

 18d8, vol. XLiv, p. 11. 



" Here are also, for convenie.u(!e' sake, included all papers beariugon the subject of 

 the origin of the guisses and crystalline schists. 



