PETROGRAPHY. 341 



(b) CONTACT METAMOKPUISM. 



Gheim, G. Die Diabas-Contactnietamorphose z>i WoiUmrj; a. d. Lahn, pp. 1-:51. One 

 plate. Ncues Jahrb., 18d«, I. Baud, Ist Heft. 



Hakker, Alfijkd. Woodwaidiau Muscnui. Notes on son)o Anglesey Dyke.s. Gcol. 

 Mag., September, 18d7, p. 409. 



Describes the rocks ns Angite-andesites, and Dolerites. A dike of tbe latter 

 rock at Plas-Nevvydd is described as having at contact converted a bed of cal- 

 careous shale into "a kind of lydianite, containing calcite and clnsters of garnet 

 and analcime crytals." 



Richards, Gary F. Lithological note on Contact Plienoniena in South Carolina. 

 Bull. Denison University, Parts i and ii, vol. iv, 188rt, pp. o-lO. 



Steciier, Er.vst. Coutacterscheinungen an schottischen Olivindiabasen. Min. 

 u. pet. Mittheiluugen, ix. Band, n u. lU Heft, pp. 14r)--J0r>. One plate showing 

 niicrostrncture. 



Williams, George H. The contact nictaniorphisni produced in the adjoining Mica- 

 schists and Limestones by the Massive Rocks of the '• Cortlaudt Series" near 

 Peekskill, New York. Am. Jour. Sci., October, 1888, vol. XXXVI, pp. 259-^69. 

 One plate showing micro-structures. 



(c) REGIOXAL METAMORPHISM." 



Barrois, C. Modifications et Transformations des Grannlites du Morbihan, Lille, 

 ir«i7. Annales Soc. Geul. du Nord, xv, 1887. 



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

 Brittany. Quar. Jour. Geol. Soc, August, 1887, vol. XLiii, No. 171, p. 301. 



Discusses the structures of the crystalline shists and their probable origin ; 

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

 sive masses and the resemblance of such secondai-y structures to gneisses and 

 schists commonly regarded as of Archtean age. The rocks carry, besides glauco- 

 phane, abundant garnets, epidote, green hornblende, white mica, quartz, sphene, 

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

 banded, the banding being produced by a predominance of epidote or sometimes 

 glaucophane. The rocks are sometimes extraordinarily rich in glaucophaue, 

 though the individual crystals are not generally large. The wiiter 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 conditi<m. 

 The rock appears iuterstratified with the adjacent schists; but, nevertheless. Pro- 

 fessor Bonney is inclined to regard it as an eruptive, altered by pressure. He has 

 further tlescri bed the gneisses of the district around QuimperM with especial ref- 

 erence to their original and seccmdary structures, and the gneisses, granites, and 

 amphibolitos of the Roscoft" and Morlaix district. His conclusions are that while 

 both igneous and stratified rocks have undergone a certain amount of pressure 

 mctamorpliism, the igneous rocks being converted into gneisses and schists, yet 

 many of the Brittany gneisses and schists were evidently true foliated rocks 

 anterior to the earth movements. Contact metamorphism produced by igneous 

 rocks on the Paleozoic sediments does not produce rocks which resemble the pre- 

 sumable Archaian gneisses and schists. 



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



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

 1888, vol. XLiv, p. 11. 



* Here are also, for convenience' sake, included all papers bearing on the subject of 

 the origin of the guisses and crystalline schists. 



